Chem 2500 - The last chem

idk to be happy or scared :((((((

l = 0 corresponds to the 1s orbital – an s orbital has no

angular nodes

l = 0 corresponds to the 2s orbital – still no

angular nodes, has 1 radial node

l = 1 corresponds to the 2p orbitals – a p-orbital has

one angular node, no radial nodes

l = 0 corresponds to the 3s orbital – still no

angular nodes

l = 1 corresponds to the 3p orbitals – a p-orbital has

one angular node, 1 radial node

l = 2 corresponds to the 3d orbitals – a d-orbital has

two angular nodes

Removing electrons leads to an increase in

Z_eff (less shielding) so  metal cations have smaller ionic radii than the neutral metals

Adding electrons leads to more shielding (larger Z_eff) and anions have larger

•ionic radii than neutral atoms.

As Z_eff increases across a group then (the magnitude of) the

electron affinity increases.

As Z_eff decreases down a group then (the magnitude of) the electron affinity

decreases

AX₃

trigonal planar’

AX₂E

‘angular’ (or ‘bent’)

AX₄

tetrahedral

AX₃E

trigonal pyramidal’

AX₂E₂

angular

AX₅

‘trigonal bipyramidal’

AX₄E 

see-saw’

AX₃E₂

T-shaped’

AX₆

‘octahedral’

AX₅E

‘square-based pyramid’

AX₃E₃

‘T-shaped’

AX₄E₂  

square planar

AX₂E₃

linear’

A or B

singly degenerate’ representation labels  

E

•doubly degenerate’

T

•‘triply degenerate’

on descending the group, the s-p separation increases and it becomes increasingly harder to promote the

electrons to become involved in bonding – inert pair effect.

Fluorine is sufficiently strong oxidizer to form the group oxidation state (+6), but chlorine can only achieve

+4 (reflecting inert nature of the lone pair)

On descending the group s-p separation increases – promotion energy gets larger – the lone pair has more s-character and

p-orbitals are primarily used in bonding... bond angles get closer to 90o on descending the group

Steric effects – bond angle increases to

accommodate larger size of Cl and then
Br