5.3.1 transition elements

transition metal requirements

• ions have a partially filled d block subshell

• variable oxidation states

• coloured compounds

ligand

any atom, ion or molecule which can donate a pair of electrons to a metal ion

are ligands electrophiles or nucleophiles

nucleophiles

monodentate ligand

forms one dative covalent bond

bidentate ligand

forms two dative covalent bonds

multidentate ligand

forms more than two dative covalent bonds

coordinate bond

dative covalent bond to a central metal ion

coordinate number

number of dative covalent bonds a metal ion makes

why do chloride ions create metal ions with lower coordination numbers

larger ion, greater steric repulsion

why are compounds coloured

• partially filled d-subshell

• electrons move between orbitals

• ligands cause partially filled d-subshells to split

• d orbitals have different energy levels

• electrons promoted to higher energy orbital

• absorbs particular frequency of light

• light transmitted/emitted