Unit 5 Flashcards
Transition metals
What is a transition metal?
A metal which doesn’t have completely filled d orbitals and can form stable ions
What is different about D-block electron filling to most other elements?
The 4s orbital occupies a higher energy level than 3D so is the first lost
Why are d-block elements more likely to show varied oxidation states?
Because they their 4S and 3D orbitals are close together in energy so the ionisation energies between 1st ie 2nd ie and third ie aren’t that different and the release of energy is much more than it takes to ionise
What is a complex ion?
metal ion centre with a number of molecules surrounding it (ligands) they are usually attached by dative bonds
What are ligands?
Molecules that bond to a metal, they usually have a lone pair that is used to form dative bonds with the metal
What happens when a ligand bonds to a transition metal?
There are repulsions between electrons in the ligands and the electrons in d block. This raises the energy in some d orbitals causing them to split.
Why are transition metal complexes coloured?
Ligands cause D-orbital splitting. When light is passed through it can be used to promote an electron between d orbitals. Energy of a particular colour will be absorbed to do the promoting, what isn’t absorbed is what colour we see
Why do the d orbitals get split to different energy levels, why aren’t they degenerate?
The way the orbitals are orientated. Some are in between axis and the other 2 are along it. Lone pairs approach via the axis and so the two orbitals on the axis feel the most repulsion and are sent to a higher energy
Why don’t non transition metal complexes have colours?
Colour is produced when energy is absorbed to promote electrons between d orbitals. Those without partially filled d orbitals cannot promote
Give some properties of transition metals
Large charge to radius ratio
have high melting and boiling points
Show variable oxidation states
What do you need to remember when filling d block orbitals?
4S is at a higher energy level in this case
Why do d block elements have high boiling points?
Metallic bonding
What are the d orbitals called within a plane? (within axis)
t2g
What are d orbitals called along the axis?
eg
Which d orbitals split to a higher energy?
eg
Which d orbitals split to the lower energy?
t2g
What is a monodentate ligand?
It donates one lone pair to the metal
What colour will be produced by a small split in d orbitals
Green (less energy needed to promote between e levels)
What colour will be produced by a large split in d orbitals?
Yellow (more energy needed to promote between e levels)
How can you work out the energy gap between d orbitals?
e= hf
or
e= hc/wavelength
What is low spin?
Electrons would rather pair together than separate as it costs more energy to promote them to next energy level Diamagnetic usually
What is high spin
When electrons occupy orbitals singly, they have been given enough energy to overcome the energy difference in orbitals. Its paramagnetic usually
what is a paramagnetic complex?
One with at least one unpaired electron. (one electron in an orbital instead of two)
What is a complex called when all electrons are in pairs?
Diamagnetic
Does the charge of a metal affect the crystal field splitting?
Yes
