## linear vs bent question

Vana Mirzakhani 3I
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

### linear vs bent question

How come for trigonal planar geometry and for tetrahedral geometry if the number of bonded electrons (coordination number) is 2, the molecular geometry is bent but for trigonal bipyramidal when the number of bonded electrons is 2, the molecular geometry is linear - not bent? Thank you in advance!

kateminden
Posts: 63
Joined: Fri Sep 28, 2018 12:24 am

### Re: linear vs bent question

Hi! Whether a molecule is bent or linear depends on if it has a lone pair. Lone pairs push the other bonds away, creating a bent or angular shape. For example, CO2 is a linear molecule because it does not have a lone pair, but H2O is a bent molecule because of the lone pairs on the oxygen atom.

Celeste 1I
Posts: 44
Joined: Fri Sep 28, 2018 12:18 am

### Re: linear vs bent question

I think the bent shape comes from a third region of electron density being a lone pair. So the lone pair pushes the other two atoms down.

Andreana Vetus 1A
Posts: 28
Joined: Fri Sep 28, 2018 12:17 am

### Re: linear vs bent question

The bent shape is a result of the lone pair. In a trigonal planar shape where there is one lone pair present, the molecular shape is bent because the lone pair repels or pushes away the two surrounding atoms.

deepto_mizan1H
Posts: 65
Joined: Fri Sep 28, 2018 12:16 am

### Re: linear vs bent question

In addition to the great explanations above, the lone pairs become very important in differentiating certain compound models due to their repulsive forces, which also directly changes the bond angles. They are tricky but important for understanding the compounds better.

Brian Hom 2F
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: linear vs bent question

When there are five areas of electron density and only two bondings pairs, the molecular shape is linear since the unbonded electrons are in the equatorial plane and they cancel each other's repulsion, leaving the bond angle to be 180. For the tetrahedral and trigonal planar geometry, when there are two bonds, the shapes are bent because the unpaired electrons repel.

Posts: 64
Joined: Fri Sep 28, 2018 12:26 am

### Re: linear vs bent question

The bent shape comes from the lone electron pair because that region counts as an area of electron density. That lone pair causes a repulsion for the other electrons which push the other bond angles closer together.

Selina Bellin 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:25 am

### Re: linear vs bent question

bent aka angular happens when a linear looking molecule has an area of electron density surrounding the central atom that consists of a lone pair