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Flashcards in Shapes Of Molecules And Ions Deck (12)
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1

What is electron pair repulsion theory?

A model used in chemistry for explaining and predicting the shapes of molecules. Electrons have a negative charge so electron pairs repel each other. Applies to ions too

2

Why is electron repulsion theory useful?

The electron pairs surround a central atom determine the shape of the molecule or ion
The electron pairs repel one another so they are arranged as far as possible from each other, minimises repulsion and hold bonded atoms in a definite shape.
Different numbers of electron pairs give different shapes.

3

How to draw in 3D

Solid line, bond on plane
Wedge, bond out of plane
Dashed line, bond into plane

4

Compare the strengths between bonded pairs and lone pairs in terms of repulsion

2 bonded pairs are less repulsive than 2 lone pairs.

5

What is the bond angle?

The angle between the bonded pairs of electrons

6

What is the rule for bond angles

The bond angle is reduced from 109.5 minus 2.5 for every lone pair in molecules with 4 electron shapes.

7

What shape do you get?
4 bonded pairs/regions
0 lone pairs

Tetrahedral
109.5

8

What shape do you get?
3 bonded pairs/regions
1 lone pairs

Pyramidal
107

9

What shape do you get?
2 bonded pairs/regions
2 lone pairs

Non linear
104.5

10

What shape do you get?
2 bonded pairs/regions
0 lone pairs

Linear
180

11

What shape do you get?
3 bonded pairs/region
0 lone pairs

Trigonal planar
120

12

What shape do you get?
6 bonded pairs/regions
0 lone pairs

Octahedral
90