Inorganic Chemistry - 1)c) Transition Metals

Question 1

what are the five main properties of transition metals?

Answer 1

*has atoms or ions with an incomplete d-subshell
*can form complexes
*has variable oxidation states
*shows catalytic ability
*forms coloured ions

Question 2

two examples of oxidising agents:

Answer 2

acidified permanganate
acidified dichromate

Question 3

what is a complex?

Answer 3

consists of a central metal ion or atom surrounded by ligands

Question 4

what is a ligand?

Answer 4

Ligands may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds

Question 5

what term is used to describe the dative covalent bonds formed between ligands and central metal atoms?

Answer 5

coordinate bonds

Question 6

what is a monodentate ligand?

Answer 6

ligands that form only one co-ordinate bond to the central atom

Question 7

what is an example of where quadridentate ligands may occur?

Answer 7

haemoglobin

Question 8

what is the coordination number?

Answer 8

the number of coordinate bonds from the ligand to the central metal ion

Question 9

what is referred to as Lewis bases?

Answer 9

ligands- since they donate electrons

Question 10

what is referred to as Lewis acids?

Answer 10

metals-since they accept electrons

Question 11

State how transition metals can act as catalysts:

Answer 11

*they have unpaired d electrons
*variable oxidation states

Question 12

how do the d-orbitals split?

Answer 12

when ligands approach along the x, y and z axes, the lone pair of the ligand repels the d-orbitals. the d-subshell splits into two distinct sets of orbitals that have a difference in energy

Question 13

what effects the size of the energy gap (split) between the d-orbitals?

Answer 13

*oxidation state of transition metal
*type of ligand
*transition metal ion

Question 14

what ultimately determines the colour that the complex produces?

Answer 14

the size of the split

Question 15

order of splitting from smallest to largest:

Answer 15

Iodide
Bromide
Chloride
Fluoride
Water
Ammonia
Cyanide

Question 16

what causes transitions of d-electrons between lower energy orbitals (ground state) and higher energy orbitals (excited state)?

Answer 16

absorption of energy from visible light

Question 17

what can be used to determine the concentration of transition metals in solution?

Answer 17

absorbance of visible or ultraviolet light

Question 18

how can the absorbance of visible or ultraviolet light be used to determine the concentration of transition metals in solution?

Answer 18

the higher the concentration of ions, the greater the absorbance

Question 19

what analytical technique can be used to determine the concentration of the ions?

Answer 19

colorimetry

Question 20

which analytical technique is used if the compound is colourless?

Answer 20

ultraviolet spectroscopy

Question 21

what is the role of a catalyst?

Answer 21

speed up a chemical reaction by providing an alternative pathway of lower activation energy

Question 22

what is a homogenous catalyst?

Answer 22

in the same state as the reactants

Question 23

what is a heterogenous catalyst?

Answer 23

different state to reactants

Question 24

what is the term used to describe the process which heterogenous catalysts work through?

Answer 24

chemisorption

Question 25

describe chemisorption:

Answer 25

the presence of unfilled d-orbitals allows for the formation of intermediate complexes. Reactant molecules are therefore absorbed onto active sites on the surface of the catalyst

Question 26

what allows transition metals to act as homogenous catalysts?

Answer 26

the variety of oxidation states