1.6 - shapes of molecules and ions

Define valence shell electron repulsion theory

valence e- pairs surrounding central atom repel to be furthest away from eachother

3 main things to remember about shapes of molecules and ions

bonding/lone pairs, bonded e- pairs influence shape same as single bonded pair, molecules 3D

What axis does each type of line represent?

— bond with paper, - - bond into paper and > bond out of paper

What are all molecules with bonded pairs only?

non-polar

AX2

2 bonded e- pairs, linear shape, 180*

AX3

3 bonded e- pairs, trigonal planar, 120*

AX2(multiple bond) O=C=O

4 bonded(2 double) e- pairs, linear, 180*

AX4

4 bonded e- pairs, tetrahedral, 109.5*

AX4(co-ordinate bond) NH4+

4 bonded e- pairs, tetrahedral, 109.5*

AX5

5 bonded e- pairs, trigonal bipyramid, 90* + 120*

AX6

6 bonded e- pairs, octahedral, 90*

AX3E

3 bonded e- pairs, 1 lone e- pair, pyramidal, 107*, polar

AX2E2

2 bonded e- pairs, 2 lone e- pairs, bent, 104.5*, polar

AX3E2

3 bonded e- pairs, 2 lone e- pairs, T-shaped, <90*, polar

AX4E2

4 bonded e- pairs, 2 lone e- pairs, square planar, 90*, non-polar

Explain shape is due to electron pair repulsion by stating:

state no. of bonded/lone pairs, e- pairs repel eachother(if only bonded - “equally”, if both “lone pairs repel more than bonded pairs”), molecule takes up shape and bond angle to minimise repulsions

What is a polar bond?

covalent bond with unequal sharing of bonding e-

When will a molecule be non-polar?

contains only non-polar bonds or equally polar bonds in symmetrical shape.