Transition metals
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define the term transition metal
one that forms atleast one stable ion with a partially filled d-subshell
Why is scandium not a transition metal
Sc3+ only ion and d-subshell is empty
Why is scandium not a transition metal
Sc3+ only ion and d-subshell is empty
what are the characteristics of transition metals
• complex ions • variable oxidation states • coloured ions • catalytic properties
What is a ligand
molecule or ion that forms a co-ordinate bond w a transition metal by donating a pair of electrons
what is a complex ion
metal ion surrounded by ligands
Name 2 bidentate ligands
• ethane-1,2-diamine ( NH2CH2CH2NH2 ) • ethanedioate ion ( C2O4 2- )
shape for [Cu(H2O)6]2+
octahedral
shape for [CoCl4]2-
Tetrahedral
shape for [Pt(NH3)2(Cl)2]
Square planar
shape for [Ag(NH3)2]+
Linear ( oxidised w tollens reagent )
Why do chloro complexes tend to tetrahedral
too big to fit anymore than 4 Cl- ligands around the metal ion
Describe the chelate effect in this reaction [Cu(H2O)6]2+ + 3 H2NCH2CH2NH2 <-> [Cu(DiAmine)3]2+ + 6 H2O
• 4 molecules on the left to 7 on the right • large increase in entropy ( thermodynamically favourable )
why is CO toxic in haemoglobin
• replaces O2 co-ordinately bonded to Fe(II) in haemoglobin bond
bond angle in Trans isomer
180
bond angle in Cis isomer
90
What is cisplatin
• effective anti-cancer drug • binds to DNA in cancer cells stopping cell replication • Two Cl- ions subbed for two N atoms on adjacent guanine bases
In a pure transition metal atom all d-orbitals are of equal energy. This is known a
ground state
in TM the presence of other atoms causes
the d-orbitals to have slightly different energies enables electrons to be excited from one d orbital to another.
When an electron moves from a lower energy d orbital to a higher energy d orbital (called the excited state) the energy needed to make the transition is taken from
white light.
why are chloride ions sometimes considered to not be ligands
too big