DEFINITION: a metal
that can form one or
more stable ions with
a partially filled
d-subshell
SCANDIUM AND ZINC: their
stable ions do not have a
partially filled d-subshell so
they are not transition
metals
PROPERTIES
PHYSICAL: good conductors of
heat and electricity, hard, strong,
high m.p and b.p
CHEMICAL: can form complex and
coloured ions, variable oxidation
states, catalysts
COMPLEX IONS: central metal ion
surrounded by coordinately bonded
ligands
LIGAND: an atom, ion or molecule that
has a lone pair of electrons that forms a
coordinate bond with a transition metal
UNIDENTATE: can only form one
coordinate bond e.g. water,
ammonia, chloride ions
BIDENTATE: form two coordinate bonds
MULTIDENTATE: can form
more than one coordinate
bonds e.g. EDTA4-
CO-ORIDNATION NUMBER: the
number of coordinate bonds
formed to a central metal ion
SHAPES: small ligands - octahedral.
Large ligands - tetrahedral. Square
planar - cisplatin.
FORMATION OF COLOURED IONS
COLORIMETRY: can be used to
determine the concentration of a
solution and/or find the ratio of
metal ions to ligands (formula)
The more conc. a solution, the more
light it absorbs so less light will pass
through the solution.
METHOD: add an appropriate ligand to intensify colour,
make up solutions of known conc., measure absorption
and transmission, plot calibration curve, measure
absorption of unknown and compare
USEFUL METHOD AS: easy to get a lot of
readings and quick, doesn't interfere
with any reactions, doesn't use up any
substances, can measure very low conc.
CATALYSTS
HETEROGENOUS: catalyst is in a
different phase to the reactants.
USE OF SUPPORT MEDIUMS: reaction happens on
the surface of catalysts so increasing the surface
of the catalyst will increase the ROR. To do this a
support medium is used e.g. catalytic converters
have a ceramic lattice coated with a thin layer of
rhodium
HOMOGEOUS: catalyst is in the
same phase as the reactants
CATALYST POISONING: Impurities can bind to the active sites on the
surfaces of heterogenous catalysts and block the reactants from being
adsorbed - reduces the surface area available to reactants.
CATALYTIC CONVERTERS: lead can
coat the surface of catalyst
HABER PROCESS: hydrogen produced from methane which is
produced from natural gas so contains impurities including
sulphur compouds. Sulphur is adsorbed onto the iron forming
iron sulphide and reducing efficiency of catalyst
AUTOCATALYSIS: one of the products is a
catalyst for the reaction. Reaction starts
slowly at the uncatalysed stage, reaction
speeds up at the catalysed stage