3.6 The shapes of molecules and ions

Question 1

What is electron pair repulsion theory?

Answer 1

• each pair of e- around the atom will repel all other e- pairs
• take a position as far apart possible to minimise repulsion

Question 2

Name of shape of 2 electron pairs of e-

Answer 2

Linear
180°

Question 3

Name of shape of 3 electron pairs of e-

Answer 3

Trigonal planar
120°

Question 4

Name of shape of 4 electron pairs of e-

Answer 4

Tetrahedron/ tetrahedral
109.5°

Question 5

Name of shape of 5 electron pairs of e-

Answer 5

Trigonal bipyramid
120°, 90°

Question 6

Name of shape of 6 electron pairs of e-

Answer 6

Octahedral
90°

Question 7

Types of tetrahedrals

Answer 7

• tetrahedral
• trigonal pyramid
• non-linear

Question 8

Trigonal bipyramid

Answer 8

4 pairs of electrons
- 1 of them is a lone pair

107°

Question 9

Non-linear

Answer 9

4 pairs of electrons
- 2 of them are lone pairs

104.5°

Question 10

how does repulsion increase between e- pairs?

Answer 10

bonding pair x2
lone-bonding pair
lone pairs x2 (greatest)