What is the molecular geometry of TeF₄?

The molecular shape of TeF₄ is seesaw, or AX₄E₁ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of TeF₄ has 180, 120 and 90 degree bond angles in the molecule. TeF₄ looks like this:

How do you find the molecular shape of TeF₄?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For TeF₄, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of TeF₄.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, four surrounding atoms, and one lone pair of electrons around the central atom, making it AX₄E.

Step 3: Use the VSEPR table to determine the geometry of TeF₄.

As you can see from the chart, AX₄E molecule is a seesaw shape.

Bond angles help show molecular geometry of TeF₄

The only bond angles we care about in this molecule is the F-Te-F angles. There are three different types of F-Te-F angles, axial-axial, equatorial-axial, and equatorial-equatorial. Below is a diagram which will explain this more.

As you can see from the diagram above, the equatorial-equatorial bond angle in TeF₄ is 120 degrees, the axial-axial is 180 degrees and the axial-equatorial is 90 degrees. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

But what about the lone pair? Does it affect molecular geometry of TeF₄?

The lone pair is present, just like an atom, except it is not depicted. Here is where it resides on this molecule.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It gets a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular geometry of TeF4 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of PCl₅?

The molecular shape of PCl₅ is trigonal bipyramidal, or AX₅ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of PCl₅ has 180, 120 and 90 degree bond angles in the molecule. PCl₅ looks like this:

How do you find the molecular geometry of PCl₅?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For PCl₅, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of PCl₅.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, five surrounding atoms, and no lone pair of electrons around the central atom, making it AX₅.

Step 3: Use the VSEPR table to determine the geometry of PCl₅.

As you can see from the chart, AX₅ molecule is trigonal bipyramidal.

Bond angles help show molecular geometry of PCl₅

The only bond angles in this molecule are the Cl-P-Cl angles. There are three different types of Cl-P-Cl angles, axial-axial, equatorial-axial, and equatorial-equatorial. Below is a diagram which will explain this more.

As you can see from the diagram above, the equatorial-equatorial bond angle in PCl₅ is 120 degrees, the axial-axial is 180 degrees and the axial-equatorial is 90 degrees. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It gets a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of PCl5 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of BrF₅?

The molecular shape of BrF₅ is square pyramidal, or AX₅E using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of BrF₅ has only 90 degree bond angles in the molecule. BrF₅ looks like this:

How do you find the molecular geometry of BrF₅?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For BrF₅, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of BrF₅. However, here is what it looks like. It is different because bromine is hypervalent (bromine usually prefers one bond and three lone pairs. Here it has five bonds and one lone pair)

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom (Br), five surrounding atoms (F), and one lone pair of electrons around the central atom, making it AX₅E.

Step 3: Use the VSEPR table to determine the geometry of BrF₅.

As you can see from the chart, the AX₅E molecule is square pyramidal.

Bond angles help show molecular geometry of BrF₅

The only bond angles in this molecule are the F-Br-F angles. There are two different types of F-Br-F angles: equatorial-axial and equatorial-equatorial. Below is a diagram which will explain this more.

As you can see from the diagram above, the equatorial-equatorial bond angle in BrF₅ is 90 degrees, and the axial-equatorial is 90 degrees. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

What about that lone pair?

The lone pair of the molecule resides in one of the axial positions, below the square as shown below. This means that the ELECTRONIC geometry is octahedral, even though the MOLECULAR geometry of BrF5 is square pyramidal. See more about about concept in the FAQs below.

More about VSEPR and the molecular geometry of BrF₅:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It gets a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of BrF5 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of COCl₂?

The molecular shape of COCl₂ is trigonal bipyramidal, or AX₃ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of COCl₂ only has 120 degree bond angles in the molecule. COCl₂ looks like this:

How do you find the molecular geometry of COCl₂?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For COCl₂, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of COCl₂.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, three surrounding atoms, and no lone pair of electrons around the central atom, making it AX₃.

Step 3: Use the VSEPR table to determine the geometry of COCl₂.

As you can see from the chart, AX₃ molecule is trigonal planar.

Bond angles help show molecular geometry of COCl₂

There are two different bond angles in this molecule, but they will both be the same angle. There are two Cl-C-O bond angles, and one Cl-C-Cl bond angle. Each of these will be 120 degrees.

As you can see from the diagram above, all the bond angles are 120 degrees. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It gets a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Q: What about double and triple bonds in VSEPR? Are they the same as a single bond?

A: For the purposes of VSEPR theory, yes they are. A double or triple bond will be treated the same as a single bond; it will be considered ONE substituent.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of COCl2 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of NO₂^–?

The molecular shape of NO₂^– is bent, or AX₂E using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of NO₂^– only has 134 degree bond angles in the molecule. NO₂^– looks like this:

How do you find the molecular geometry of NO₂^–?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For NO₂^–, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of NO₂^–.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, two surrounding atoms, and one lone pair of electrons around the central atom, making it AX₂E. For the purposes of VSEPR, we are determining the geometry of the nitrogen atom, so we ignore the negative charge on the oxygen.

Step 3: Use the VSEPR table to determine the geometry of NO₂^–.

As you can see from the chart, AX₂E molecule is bent.

Bond angles help show molecular geometry of NO₂^–

There is only one bond angle in this molecule. It is the O-N-O bond angle, which is 132 degrees. Even though one is a double bond and the other is a single bond, they are actually the same because of resonance, a process where the single and double bond are changing places so rapidly that they act like it is 1.5 bonds between the O and N.

Also, it is important to remember that there is a negative charge on the oxygen that has only one bond, giving the overall molecule a negative charge.

More about VSEPR and the molecular geometry of NO₂^–:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Q: What about double and triple bonds in VSEPR? Are they the same as a single bond?

A: For the purposes of VSEPR theory, yes they are. A double or triple bond will be treated the same as a single bond; it will be considered ONE substituent.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of NO2- [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of XeF₄?

The molecular shape of XeF₄ is square planar, or AX₄E₂ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of XeF₄ has only 90 degree bond angles in the molecule. XeF₄ looks like this:

How do you find the molecular geometry of XeF₄?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For XeF₄, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of XeF₄. However, here is what it looks like. It is different because xenon is hypervalent, and has four bonds and two lone pairs for an “octet” of 12.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom (Xe), four surrounding atoms (F), and two lone pairs of electrons around the central atom, making it AX₄E₂.

Step 3: Use the VSEPR table to determine the geometry of XeF₄.

As you can see from the chart, the AX₄E₂ molecule is square planar.

Bond angles help show molecular geometry of XeF₄

The only bond angles in this molecule are the F-Xe-F angles, as each F-Xe-F bond angle is the same as all of the others. Below is a diagram which will explain this more.

What about that lone pair?

The lone pairs of the molecule resides in both of the axial positions, above and below the square as shown below. This means that the ELECTRONIC geometry is octahedral, even though the MOLECULAR geometry of XeF₄ is square planar. See more about about concept in the FAQs below.

More about VSEPR and the molecular geometry of XeF₄:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of XeF4 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of BF₃?

The molecular shape of BF₃ is trigonal planar, or AX₃ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of BF₃ only has 120 degree bond angles in the molecule. BF₃ looks like this:

How do you find the molecular geometry of BF₃?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For BF₃, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of BF₃.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, three surrounding atoms, and no lone pair of electrons around the central atom, making it AX₃.

Step 3: Use the VSEPR table to determine the geometry of BF₃.

As you can see from the chart, AX₃ molecule is trigonal planar.

Bond angles help show molecular geometry of BF₃

There is only one bond angle in this molecule, the F-B-F angle. Each of these will be 120 degrees.

As you can see from the diagram above, all the bond angles are 120 degrees. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Q: What about double and triple bonds in VSEPR? Are they the same as a single bond?

A: For the purposes of VSEPR theory, yes they are. A double or triple bond will be treated the same as a single bond; it will be considered ONE substituent.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of BF3 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of ClF₃?

The molecular shape of ClF₃ is T-shaped, or AX₃E₂ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of ClF₃ only has 90 and 180 degree bond angles in the molecule. ClF₃ looks like this:

How do you find the molecular geometry of ClF₃?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For ClF₃, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of COCl₂.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, three surrounding atoms, and two lone pairs of electrons around the central atom, making it AX₃E₂.

Step 3: Use the VSEPR table to determine the geometry of ClF₃.

As you can see from the chart, AX₃E₂ molecule is T-shaped.

Bond angles help show molecular geometry of ClF₃

There are two different bond angles in this molecule. There are two F-Cl-F bond angles. One of these will be 90 degrees, the other will be almost 180 degrees. [The actual bond angle has been measured at 177 degrees, a little off from 180 degrees because of the influence of the two lone pairs.

As you can see from the diagram above, the bond angle can be either 90 or about 180 degrees, depending on which two F atoms you are going between. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

What about that lone pair and how it affects the molecular shape of ClF₃?

The lone pairs of the molecule resides in both of the equatorial positions, as shown below. This means that the ELECTRONIC geometry is trigonal bipyramidal, even though the MOLECULAR geometry of ClF₃ is T-shaped. This is not the best representation in the world, but the two lone pair orbitals are coming out of the screen at you and going into the screen. See more about about concept in the FAQs below.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Q: What about double and triple bonds in VSEPR? Are they the same as a single bond?

A: For the purposes of VSEPR theory, yes they are. A double or triple bond will be treated the same as a single bond; it will be considered ONE substituent.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of ClF3 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of SF₆?

The molecular shape of SF₆ is octahedral, or AX₆ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of SF₆ only has 90 and 180 degree bond angles in the molecule. SF₆ looks like this:

How do you find the molecular geometry of SF₆?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For SF₆ it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of SF₆.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, six surrounding atoms, and no lone pair of electrons around the central atom, making it AX₆.

Step 3: Use the VSEPR table to determine the geometry of SF₆.

As you can see from the chart, AX₆ molecule is octahedral.

Bond angles help show molecular geometry of SF₆

The are two different bond angles in this molecule, both are F-S-F bond angles. One of them is 90 degrees, the other is 180 degrees, as shown below:

This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Q: What about double and triple bonds in VSEPR? Are they the same as a single bond?

A: For the purposes of VSEPR theory, yes they are. A double or triple bond will be treated the same as a single bond; it will be considered ONE substituent.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular Geometry of SF6 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.

What is the molecular geometry of XeF₂?

The molecular shape of XeF₂ is linear, or AX₂E₃ using Valence Shell Electron Pair Repulsion (VSEPR) theory. Hence, the molecular geometry of XeF₂ has a 180 bond angle in the molecule. XeF₂ looks like this:

How do you find the molecular shape of XeF₂?

There is an easy three-step process for determining the geometry of molecules with one central atom.

Step 1: Determine the Lewis structure of the molecule.
For XeF₂, it is as shown below: For a full-explanation of how to figure out the Lewis structure, please go to Lewis Structure of XeF₂.

Step 2: Apply the VSEPR notation to the molecule.
Apply VSEPR notation, A X E
A=Number of central atoms
X=Number of surrounding atoms
E= Number of lone pairs on central atom
For this one, we can see that it has one central atom, two surrounding atoms, and three lone pairs of electrons around the central atom, making it AX₂E₃.

Step 3: Use the VSEPR table to determine the geometry of XeF₂.

As you can see from the chart, AX₂E₃ molecule is a linear shape.

Bond angles help show molecular geometry of XeF₂

The only bond angles we care about in this molecule is the F-Xe-F angle, which is the only angle in the molecule. Below is a diagram which will explain this more. This geometry allows for substituents (atoms and lone pairs) to be as far apart from each other as possible.

But what about the lone pairs? Does it affect molecular geometry of XeF₂?

The lone pairs are present, just like an atom, except they are not depicted. Here is where it resides on this molecule.

Remember, XeF₂ is in the trigonal bipyramidal “family”. More on this below. So the MOLECULAR GEOMETRY of XeF₂ is linear, but the ELECTRONIC GEOMETRY is trigonal bipyramidal. Check out the FAQ section for a bit more explanation on this concept.

More about VSEPR:

Let’s not forget, the whole purpose of VSEPR is to minimize interactions between the substituents (atoms and lone pairs) of a molecule. We also know that electrons repel each other. Hence, simple molecules (like the ones we are looking) at will tend to place substituent atoms as far from each other as possible. We know this because of the bond angles associated with each of the four types of shapes.

Here is one way to remember this chart: Think about each lone pair as just replacing an atom. In the chart above we have tried to show how this works by just blurring out an atom for a lone pair.

For the 3 and 4 substituent molecules (AX₃ group and AX₄ group, respectively) it is easy to do this because each one of the substituent atoms is the same. So for AX₂E, it is simple to see that we get trigonal pyramidal as the answer because we can replace any of the atoms with a lone pair because they are all geometrically equivalent. Same for AX₃E because all of the atoms are geometrically equivalent.

It get a little trickier when we get to the 5 and 6 substituent molecules (AX₅ group and AX₆ group, respectively). Here, there is a geometric difference between the atoms on the axis (called axial substituents) and the ones around the middle, called the equatorial substituents. Thus, we can’t just substitute a lone pair for any old atom. So…..what we need to remember is that for the AX₅ group, you need to replace equatorial atoms with lone pairs AND for the AX₆ group, you need to replace the atoms on the axis with lone pairs, as we have shown above.

Some video to make it a little simpler:

FAQs:

Q: Are these bond angles exact for each molecule?

A: No, the bond angles are slightly influenced by whether the substituent is an atom or a lone pair and by atomic radii. Hence, the bond angles shown are close estimations, and not exact. A good example of this is methane and ammonia, as shown below. The lone pair in ammonia has a different repulsion effect than the hydrogen of methane, and therefore a slightly different bond angle.

Q: Does VSEPR theory work for more complex molecules?

A: Yes, it can, however, it is important to remember that VSEPR is a tool and has its limits. One way you can use VSEPR is to call a group of atoms one substituent. Below is an example of this.

In the example above, we will only examine the carbon furthest to the left. VSEPR predicts this will be a tetrahedral carbon atom as it has the AX₄ configuration of four bonded groups and no lone pairs, as we treat each hydrogen atom as a separate substituent and the everything else residing to the right of the carbon as one substituent.

We can do the same thing for the carbon second from the right, as shown in the image above. Each blue bubble represents a different substituent group (or atom) coming off of that carbon. As you can see, there are three blue bubbles of substituents and no lone pairs, meaning the VSEPR notation at this specific carbon is AX₃, meaning it will be trigonal planar.

For more on this, please see our VSEPR guide at VSEPR molecular shape study guide

Q: What is the difference between the molecular geometry and the electronic geometry of a molecule?

A: The molecular geometry only takes atoms into account, whereas electronic geometry accounts for both atoms and lone pair electrons. This means that the electronic geometry and the molecular geometry can be different for the same molecule. Take for example CF₄ and H₂O. Both have tetrahedral electronic geometry, however H₂O has a bent molecular geometry while CF₄ has a tetrahedral molecular geometry (because the carbon of CF₄ does not have any lone pairs).

Q: Does the steric group attached to the central molecule affect the bond angle?

A: Yes, it can. A good example of this is NH₃ (ammonia) vs. tert-butyl isopropyl amine (TBIPA). While both of these molecules have a central nitrogen atom and are both AX₃E molecules, they have different substituents coming off of the nitrogen. TBIPA is just ammonia with two of the hydrogens replaced by large hydrocarbons that want to be far apart from each other. Because of this, those large groups will move away from each other and have a larger bond angle than a similar molecule with just hydrogen atoms there. Therefore, even though both molecules are AX₃E, they don’t have the same bond angles.

Lastly, here is the printable study guide!

This is our study guide. It is downloadable, printable and sharable. VSEPR molecular geometry study guide

The post Molecular geometry of XeF2 [with video and free study guide] appeared first on Organic Chemistry Made Easy by AceOrganicChem.