Shapes Of Molecules

Question 1

Electron pair repulsion theory

Answer 1

• electron pairs repel other pairs as far apart as possible
• lone pairs repel more than bond pairs
• the number of lone and bond pairs around the central atom determines the shape of the molecule

Question 2

To find shape

Answer 2

1. Dot cross to find regions of electron density around central atom, with ALL electrons added.
2. Determine pair types
3. -2.5 per lone pair
   4.Line wedge dash clearly

Question 3

2 bond pairs shape and angle

Answer 3

Linear, 180

Question 4

3 bond pairs shape + angle

Answer 4

Triagonal planar, 120

Question 5

2 bond, 1 lone pair shape + angle

Answer 5

Tiagonal planar, non linear, 117.5

Question 6

4 bond pairs shape + angle

Answer 6

Tetrahedral, 109.5

Question 7

3 bond, 1 lone pair, shape + angle

Answer 7

Tetrahedral pyramidal, 107

Question 8

2 bond, 2 lone pairs , shape + angle

Answer 8

Non linear tetrahedral, 104.5

Question 9

6 bond pairs shape + angle

Answer 9

Octahedral, 90

Question 10

4 bond 2 lone pairs, shape + angle

Answer 10

Octahedral, square planar, 90

Question 11

what is the shape and bond angle of SO2

Answer 11

two double bonds and one lone pair
double bonds have a similar repelling effect to
the lone pair and the three regions of electron density repel one another as
far apart as possible.

120°, non-linear

Question 12

bonding in NH3

Answer 12

1 dative covalent between N and H

Question 13

bonding in H3O+

Answer 13

1 dative covalent

Question 14

SO4^2- bonding

Answer 14

The central S atom is bonded to the four O atoms by two double bonds
and two single bonds.
@ The two O atoms with single bonds each contain one ‘extra’ electron,
shown by a triangle. This gives each O atom a full outer shell.
@ The 2- charge on the ion results from the two extra electrons.
v tetrahedral shape with equal bond
angles of 109.5°.