Flashcards in 2.5(P1) Transition Metals Deck (31)
What is the definition of transition metals?
One that forms at least one stable ion with a part-full d sub level of electrons
What are some properties of transition metals?
Good conductors of heat electricity
Low chemical reactivity
High melting and boiling points
All are in the d block, not all d block are transition metals
When ions form they lose an electron in the s sub-level not d
What two elements don’t fit the pattern of electron configuration?
What are the 4 main characteristics of transition metals?
Form coloured compounds
Have variable oxidation states
Have catalytic activity
This all results from their electronic structure
What is different about transition metals to normal metals?
The form co-ordinate bonds instead of a weak electrostatic force like most metals
This is due to a partially filled 3d sub-level
What are complexes?
A transition metal surrounded by ligands
Which are co-ordinately bonded to the (ion) in the middle
How do you draw a complex?
The metal (ion) in the middle
Surrounded but the ligand (eg water)
Arrows between the two to show the co-ordinate bond
All contained within square brackets
The charge of the metal ion if it has one on the outside (because water is neutral so it isn’t changed)
What is the co-ordinate number?
The number of co-ordinate bonds
Can you have a complex without a charge?
It’s just a complex
Not a complex ion
What is a ligand?
A ligand is a species that can donate one or more lone pairs to form a co-ordinate bond to the transition metal
How is the ligand water involved in complexes?
Only one of it’s two lone pairs are used in co-ordinate bonding
As one of the lone pairs faces the opposite direction
Why can transition metals form complexes?
They have a partially filled 3d sublevel
What are the names for complexes with a co-ordination number of:
6 = octahedral
4 = tetrahedral or square planar
2 = linear
What is a unidentate ligand?
Forms a single co-ordinate bond no matter how many lone pairs it has
What should you be careful of when working out the charge on a complex?
If the ligand also has a charge which should be taken into account with the metal (ion)
I.e chloride and cyanide
What is a bidentate ligand?
They have lone pairs on different atoms so can ‘bend’ round to form 2 co-ordinate bonds
Examples of a unidentate ligand?
Give some examples of a bidentate ligand?
1,2 - diaminoethane(no charge)
Ethanedioate ion (2-)
Which comes from having 2 carboxyl groups on each end with the hydrogens removed
1,2 - dihydroxybenzene (no charge)
Why must you be careful with bidentate ligands?
It could be forming 6 co-ordinate bonds however this would only be from 3 ligands
As each bidentate ligand supplies 2 lone pairs
What bidentate is abbreviated and what to?
1,2 - diaminoethane
Is abbreviated to
What is a multidentate ligand?
They have more than one atom with a lone pair that they can donate
Give an example of a multidentate ligand?
22 lone pairs
Only 6 lone pairs are used
A lone pair from each of the 4 outer oxygens
A lone pair from the 2 nitrogens
What is the chelate effect?
If you add EDTA to a solution of a transition metal salt, EDTA will replace all 6 water ligands in the aqua ion
2 reactants are replaced by 7 products therefore an increase in entropy moves the reaction to the right
Therefore polydentate ligands are favoured over monodentate ligands
What are bridges?
A bidentate ligand can form a bridge between 2 metal ions (almost like a polymer)
Describe the prosthetic group haem?
The oxygen it carries forms a temporary co-ordinate bond
CO - carbon monoxide can join instead of O2 forming a permeant bond
What is Cisplatin?
Platinum with 2 chlorine ligands and 2 ammonia ligands (same ligand on the same side)
Used to treat some types of cancer in chemotherapy
What is significant about transplatin? Why?
Transplatin or E-platin
Doesn’t work in chemotherapy
As cisplatin has a higher melting point as in more soluble due to it being polar (ligands on the same side = more EN)
What complexes do you draw if asked for:
Linear: Ag(silver) with 2 ammonia ligands = 1+ complex
(Used in tollen’s reagent)
Tetrahedral: Co(cobalt) with 4 chlorine ligands attached = 2- complex
Octahedral: Fe(iron) with 6 water ligands attached = 2+ complex
What do you draw if they want an octahedral shape using a bidentate ligand?
Co(cobalt) with 3 ethandioate ions = 4- complex