5.3.1 transition metals

Question 1

transition metal

Answer 1

a d-block element with an incomplete d sub-shell

Question 2

transition metal exceptions

Answer 2

zinc - forms 2+ ion which has a complete d orbital

sc - forms 3+ ion which has an empty d orbital

Question 3

properties of transition metals

Answer 3

have more than one oxidation state e.g. Fe2+ and Fe3+

Formation of coloured compounds [Cu(H2O)6]2+ is pale blue, [CuCl4]2- is yellow

can act as catalysts e.g. iron in haber process, V2O5 in contact process

Question 4

complex ion

Answer 4

transition metal ion bonded to one or more ligands by coordinate bonds (dative covalent bonds)

Question 5

ligand

Answer 5

molecule or ion that can donate a lone pair of electrons to transition metal ion to form a coordinate bond e.g. OH2, NH3, CN-

Question 6

coordinate bond

Answer 6

shared pair of electrons in which the bond pair has been provided by one of the bonding atoms only

Question 7

coordination number

Answer 7

number of coordinate bonds formed to a central metal ion

Question 8

bidentate ligands

Answer 8

molecule or ion that can donate 2 pairs of electrons with the transition metal ion to form 2 coordinate bonds

Question 9

examples of octahedral complexes

Answer 9

[Co(NH3)6]2+

[Cu(H2O)6]2+

many hexaaquo complexes

Question 10

examples of tetrahedral complexes

Answer 10

[CoCl4]2-

many tetrachloro complexes

Question 11

examples of square planar complexes

Answer 11

cisplatin PtCl2(NH3)2

complexes of Pt

Question 12

linear complex

Answer 12

[Ag(NH3)2]+

Question 13

cisplatin

Answer 13

used as anti-cancer drug

2 chloride ions are displaced and molecule joins onto the DNA, stopping replication of cancerous cells

1 Cl ligand substituted by water molecule in body

Question 14

[Cu(H2O)6]2+ + Cl-

Answer 14

[Cu(H2O)6]2+ + 4Cl- > [CuCl4]2- + 6H2O

blue > yellow/green solution

Question 15

[Co(H2O)6]2+ + Cl-

Answer 15

[Co(H2O)6]2+ + 4Cl- > [CoCl4]2- + 6H2O

pink > blue solution

Question 16

haemoglobin O2 importance

Answer 16

blood passes through lungs > haem binds to O2 due to increased O2 pressure in capillaries of lungs > oxyhaemoglobin
- releases O2 to body cells

haemoglobin can bind to CO2 > carried back to lungs and released

Question 17

Haem and CO2

Answer 17

CO2 binds to Fe2+ ion in haem > carboxyhaemoglobin

breathing in CO-ligand substitution occurs where O2 in haem is replaced by CO

CO binds to haem more strongly than O2, preventing haem from carrying O2 (irreversible)

too high of a conc of carboxyhaemoglobin > O2 transport prevented > death