4627221
Transition metals
- 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
- 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
- PHYSICAL: good conductors of
heat and electricity, hard, strong,
high m.p and b.p
- 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-
- UNIDENTATE: can only form one
coordinate bond e.g. water,
ammonia, chloride ions
- CO-ORIDNATION NUMBER: the
number of coordinate bonds
formed to a central metal ion
- SHAPES: small ligands - octahedral.
Large ligands - tetrahedral. Square
planar - cisplatin.
- LIGAND: an atom, ion or molecule that
has a lone pair of electrons that forms a
coordinate bond with a transition metal
- 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.
- The more conc. a solution, the more
light it absorbs so less light will pass
through the solution.
- 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
- 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
- CATALYTIC CONVERTERS: lead can
coat the surface 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
- HETEROGENOUS: catalyst is in a
different phase to the reactants.
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