1.4 Flashcards
Definition of transition metal
They should have at least one ion with an incomplete d-subshell. Should produce ions with different valencies; produce coloured compounds; and can act as a catalyst
Exemption to a definition
Sc and Zn only have one possible ion each, have no coloured compounds, and cannot act as catalysts. Cu has a complete d-subshell, but apart from that is fine
Oxidation number
How many electrons have been lost
Oxidation state
Ion is just the number of electrons e.g. for V3+, state would be 3
Oxidation state of transition metals
Exhibit variable oxidation states of differing stability because they not only lose 4s electrons but some or all of 3d electrons
Rules for oxidation number
Simple ions have charge of -1/1 and the sum of all oxidation numbers in a polyatomic ion is equal to overall charge of ion. Overall charge of a compound is always zero. Oxygen is always -2, hydrogen is always 1
Ligand
Molecules/ anions which attach to the metal atom in a complex via a dative covalent bonds
Anion
Negative ion
Cation
Positive ion
Monodentate ligands
One donor atom/ dative bond. E.g. water, ammonia, chlorine, cyanide (CN-), hydroxide
Bidentate ligands
Ligands with two donor atoms/ dative bonds e.g. oxalato
Polydentate ligands
Multiple donor sites/ dative bonds e.g. EDTA
Coordination compound
Cation/ anion can’t exist on their own so must have charges balanced. The complex ion will bond with oppositely charged ions to form a complex
Coordination number
Number of bonds in a complex that the metal makes with ligands
Naming coordination compounds
- Cation precedes anion
- Ligands, then metals
- Ligands have a Greek prefix
- If complex ion is an anion, it ends in -ate
- The metal name is followed by the oxidation state in Roman numerals
- Add an -ido to root name of an anion. Aqua and ammine, otherwise for neutral ligands just use name
Colours of transition metals
Ligands bonding to transition metals lead to d-orbitals splitting because they’re no longer degenerate. Electrons jump to a lower energy level, leading to colour in d-d electron transmission. If it is white, subshell is empty as it has to be partially full
Catalysts
Transition metals commonly used as catalysts due to partially filled d-orbitals and because they can change oxidation states
