Week 12 - Transition Elements

Question 1

periodic trend in transition metals

Answer 1

• size does not vary by much
• Zeff does not change much
• IE increases to the right in period 4, not in others

Question 2

Oxidization number of an atom

Answer 2

charge that the atom would have if the electrons were transferred completely to/from bonded atoms

Question 3

how to assign oxidation number

Answer 3

• atom in elemental form = 0
• monatomic ion = ion charge
• sum of ON values of atoms in a molecule = 0
• sum of ON values of atoms in a polyatomic ion = charge of the ion

Question 4

atoms/groups with specific oxidation numbers

Answer 4

group 1 = 1
group 2 = 2
H = 1 with nonmetal, -1 with metal or boron
O = -2 in most cases
group 17 = -1 in most cases

Question 5

transition metal ions colour and reason

Answer 5

often highly coloured and/or paramagnetic due to unfilled d-subshells

Question 6

low oxidation vs higher oxidation states

Answer 6

low oxidation states are more metallic / ionic, higher oxidation states are more covalent

Question 7

coordinator compound

Answer 7

transition metal center, neutral or anionic ligands (written inside square brackets)

Question 8

ligand

Answer 8

molecules or anions with one or more donor atoms - each donor atom donates a pair of electrons to the metal ion

Question 9

coordination isomers

Answer 9

same compound formula, but different composition of the complex ion

Question 10

geometry vs isomers

Answer 10

linear - none
square planar - can
tetrahedral - can

Question 11

naming a coordination compound

Answer 11

• metal first, then ligands
• counter ions go outside square brackets
• cations first, then anions
• alphabetical order
• if ligand contains a prefix (like ‘di’, then use bis-, tris-, tetrakis-, pentakis-)
• roman numerals denote oxidation number of central metal ion
• if -ve charge, ‘-ate’ added to metal (iron special ending: ferrate)
• if +ve charge just write as normal

Question 12

give name of each neutral ligand: NH3, H2O, NO, en, CO

Answer 12

ammine, aqua, Nitrosyl, ethylene diamine, carbonyl

Question 13

give name of each anionic ligand: Cl-/F-, NO2-, CN-, OH-, C2O42-

Answer 13

chloro/fluoro, nitro, cyano, hydroxo, oxalato

Question 14

crystal field theory (CFT)

Answer 14

describes the breaking of orbital degeneracy in transition metal complexes due to the presence of ligands

Question 15

strong field ligands

Answer 15

more electron density, more repulsion of the particular d orbitals, higher energy difference as compared to ‘weak field’ ligands

Question 16

magnetic properties of coordination compounds

Answer 16

anything with unpaired electrons is magnetic, but few unpaired electrons is only weakly magnetic