Mikeh

Question 1

What happens to electrons placed in the dxy,dxz, dyz orbitals

Answer 1

These ligands point to the spaces between ligands so electrons experience less repulsion and are therefore stabilised while the others are destablilised. This is for octahedral complexes

Question 2

In tetrahedral complexes which orbitals are stabilised

Answer 2

The two which lie along the axis are stablilsed and the ones pointing towards ligands are destablised.

Question 3

In square planar complexes which orbitals are stabilised

Answer 3

The ones with Z components

Question 4

What three things effect delta Oct

Answer 4

oxidation - higher oxidation higher the value
Row of metal - Down a row delta oct increases
The type of ligand - weak field give rise to small values and strong field gives rise to large values.

Question 5

How do you find the energy of a peak

Answer 5

E = hc

h is planks and c = speed of light/ wavelength in m

multiply that by avagadros and divide by 1000

Question 6

Why is the peak so large on aabsorption graph

Answer 6

molecules are vibrating, Different lenght of M - L cause different values in delta Oct. If its a long bond then there is less repulsion felt between ligands and electrons so delta oct is less and absorption will move to lower energy (longer wavelenght)

and vice versa

Question 7

Why is there a peak going up at the beginning of the spectra

Answer 7

Charge transfer absorption

Question 8

why is there a shoulder

Answer 8

2 possible transitions from dxy to either dx²-dy² dx², so you get absorption of light of two different wavelenghts anf hence two peaks.

Question 9

What is tetragonal compression

Answer 9

if electrons are put into dx²-dy² then electrons on x and y axis feel extra repulsion and move out along the x and y axis. Ligans on z axis feel less and move in a bit, so you get 4 long and 2 short bonds.

dxy and dx²-dy2 move down in energy as they are stabilised.

Question 10

What is tetragonal elongation

Answer 10

putting electrons in dz² means elctrons in the z axis are repelled and move out along axis. ligands on x and y aixs feel less and move in.

orbtials containing a z component are stabilised and move down in energy while the others are destablised.

Question 11

what is jahn teller distortion

Answer 11

A molecule in a degenerate electronic state will undergo a geometrical distortion to remove the degeneracy

Question 12

what is hydration energies

Answer 12

Enthalpy change for the reaction of a mole of gaseous M²⁺ with a infinite number of water molecules to give a hydrated cation.

Question 13

How does the hydration energies change as you go across the period.

Answer 13

More exothermic beacause the size of the metal gets smaller so higher charge density so interaction gets stronger.

double humped curve. This is because water is a weak field ligand so all high spin except at d³ and d⁸.

Question 14

How does the ionic radius change across the period

Answer 14

Gets smaller, d orbitals are occupied and are poor shidlders of nuclear charge.

Question 15

Why are tetrahedral complexes favoured

Answer 15

6 bonds rather than 4 bonds. Delta oct is bigger than delta tet.

Question 16

How to form tetrahedral complexes

Answer 16

large negatively charged weak field ligands

use 1st row metals

Question 17

How to form sqaure planar complexes

Answer 17

Tendacy to form square planar increases as delta tet does. Pt and Pd will from sqaure planar to avoid filling the dx²-dy².

Question 18

How do you make complexes

Answer 18

By substitution reactions, replacing one ligand by another

Question 19

What is the inner coordination sphere

Answer 19

Molecules attached to the metal

Question 20

What is the outer coordination sphere

Answer 20

loosely bound molecules which surround the complex

Question 21

What is aquation

Answer 21

replacing a ligand by water

Question 22

what is anionation

Answer 22

neutral ligand is replaced by an anion

Question 23

how can you influence which compound you crystalise

Answer 23

by changing counter ions

Question 24

What does labile and inert mean

Answer 24

Labile - fast and rapid substitution
Inert- slow substitution eg mins,day or weeks

Question 25

why are hexa aqua ions acidic

Answer 25

the metal is electropositive and take e density from O making the H more acidic.

Question 26

What is the chelate effect

Answer 26

enhanced stability of complex containing chealting (polydentate) ligands over one similar monodentate ligand.

Question 27

What is the main contribution to the chelate effect

Answer 27

is entropy as delta H should not change as it is the same metal.

Question 28

what is the optimum ring number for Sp³ carbons

Answer 28

5 and 6

Question 29

Name the irving williams series for M²⁺ and why are the more stable as the series goes along

Answer 29

Ba>Sr>Ca>Mg>Fe>Co>Ni>Cu>Zn

due to electrostatic effects and ligand field effects

Question 30

what are hard acids

Answer 30

small non polarisble, highly charged metals. for example Al³⁺, Cr³⁺, Ti⁴⁺, VO²⁺

Question 31

what are soft acids

Answer 31

larger, highly charged. Moslty in groups 2 and 3 and are cations of less electropositive metals

Question 32

What are soft bases

Answer 32

large and more polarisable. most second row elements excpet for CO and CN.

Question 33

What are hard bases

Answer 33

small and not polarisable. first row elements.

Question 34

Give an example of when HSAB goes bad

Answer 34

Be²⁺ should be hardest cation and therefore be a hard acid but its small charge means its bery polarisable and distorts e clouds.

Question 35

what is hydrometallurgy

Answer 35

seperate one metal from a mixture of metal ores using the methods of solvent extraction.

Question 36

How are complexes used in detergents

Answer 36

Remove unwanted metal ions in hard water.

Question 37

what is chealtion therapy

Answer 37

Remove unwanted toxix metal ions from the body without affecting the beneficial ones.

Question 38

How does changing the Fe from high spin to low spin allows it to fit into the porphryin ring

Answer 38

High spin - the radius is too large to allow it to fit into the plane of porphyrin but low spin the radius is smaller and iron can fit into the plane. This cascade of conformational changes allows oxygen to bind.

Question 39

How is cis platin made

Answer 39

The trans effect.

Question 40

What is the trans effect

Answer 40

he trans effect is the labilization (making unstable) of ligands that are trans to certain other ligands