TOPIC 3

Question 1

Which elements conduct electricity

Answer 1

Sodium
Magnesium
Aluminium

Question 2

Describe silicon’s ability to conduct electricity

Answer 2

Semi-conductor

Question 3

Which element oxide is amphoteric

Answer 3

Aluminium oxide

Question 4

What does amphoteric mean

Answer 4

Both acidic or basic

Question 5

Sodium oxide and magnesium oxide produce acidic or basic solution?

Answer 5

Basic

Question 6

Which element oxides produce an acidic solution

Answer 6

All elements after aluminium

Question 7

Equation for sulfur trioxide with water

Answer 7

SO3 (g) + H2O (l) - H2SO4 (aq)

Question 8

Equation for NO2 and water

Answer 8

3NO2 (g) + H20 (l) - 2HNO3 (aq) + NO (g)

Question 9

Na2O, MgO, Al2O3

Answer 9

IONIC

Question 10

SiO2, P4O10, SO3, Cl2O7

Answer 10

COVALENT

Question 11

Describe pH trend of period 3 oxides

Answer 11

Basic to acidic

Question 12

Describe electron affinity of metals and non-metals

Answer 12

Metals have a low EA because they lose electrons and non-metals have a high EA

Question 13

Explain the pattern of electron affinity down group 7

Answer 13

Electron affinity decreases down group 7. Less energy is released if further away from nucleus because there is a lot of shielding, weaker force of attraction. Chlorine has the highest electron affinity as fluorine is the smallest atom and so has a high electron density - repels electron that is trying to get into the atom.

Question 14

Why does oxygen have 2 EA’s

Answer 14

1st EA - exothermic like everything else

2nd - endo - due to electron getting into negative ion and energy needs to be put in to overcome the repulsion

Question 15

Why are cations smaller than parent?

Answer 15

Because electrons are lost, # of shells decreases. Also, shielding decreases, stronger force of attraction. Nuclear charge increases.

Question 16

Why are anions larger than parent

Answer 16

Extra electrons increase repulsion, increase shielding, weaker electrostatic force of attraction

Question 17

Why do transition metals have variable oxidation states

Answer 17

4s and 3d are of similar energy

Their sequential ionisation energies are close together

Question 18

What are the 3 ferromagnetic metals

Answer 18

IRON
COBALT
NICKEl

Question 19

What makes a metal paramagnetic

Answer 19

Anything with lone electrons in domains

Question 20

Diamagnetic?

Answer 20

FULL ELECTRONS in domains

Question 21

Why is FeCo ligand diamagnetic and not paramagnetic?

Answer 21

use SPECTROCHEMICAL series

CO has the greatest energy difference, d-orbitals split largely

electron comes down

Question 22

Explain how the colour of solutions containing transition metals can be used to determine their concentration.

Answer 22

Prepare samples of the transition metal ion over a range of known concentrations.
Add a small quantity of a suitable ligand to each in order to identify the colour.
Choose the filter which gives the largest absorbance, and measure the absorbance of each sample using this filter.
Plot a graph of absorbance against concentration.
Take the sample of unknown concentration, add the ligand to intensify the colour, and measure its absorbance using the same filter.
Use the graph to deduce the concentration of the solution.

Question 23

State three different features of transition metal complexes that cause a change in the
value of ΔE, the energy change between the ground state and the excited state of the
d electrons

Answer 23

Identity of the metal
Charge (on the metal) / oxidation state / charge on complex
(Identity of the) ligands
Co-ordination number / number of ligands
Shape

Question 24

Why are complexes of d-orbitals coloured?

Answer 24

D-orbitals are partially filled

The d-orbitals split into 2 levels due to repulsion of electrons in ligand with electrons in d-orbitals

Energy difference between the 3 low energy d-orbitals and the 2 high energy d-orbitals corresponds to a certain frequency in the visible part of the spectrum

Electron transitions occur from the lower to higher energy level

Complementary colour is seen

Question 25

What is the coordination number?

Answer 25

The number of lone pairs bonded to the metal ion

Question 26

Why are complexes of d-orbitals coloured?

Answer 26

D-orbitals are partially filled

The d-orbitals split into 2 levels due to repulsion of electrons in ligand with electrons in d-orbitals as ligand approaches

Energy difference between the 3 low energy d-orbitals and the 2 high energy d-orbitals corresponds to a certain frequency in the visible part of the spectrum

When white light falls on solution, that energy is absorbed

Electron transitions occur from the lower to higher energy level

Complementary colour is seen

Question 27

Define ligands

Answer 27

Ligands are molecules or ions use lone pair of electrons to form coordinate covalent bonds with a central metal ion

Question 28

Define polydentate ligands

Answer 28

Polydentate ligands are species that have more than one lone pair of electrons to form coordinate covalent bonds to a central metal ion

Question 29

Physical properties of metals

Answer 29

High electrical conductivity
High melting point
High tensile strength
Malleable
Ductile

Question 30

Chemical properties of metals

Answer 30

Variable oxidation states
Formation of complex ions
Coloured compounds
Catalytic behaviour

Question 31

Describe the changes in melting point across period 3

Answer 31

Na to Al = metallic bonding, number of delocalised electrons increases, greater attraction to cations, more energy required to overcome. Also, charge density increases as atoms get smaller

Si = giant covalent, strong covalent bonds require a lot of energy to overcome

S - Ar = simple molecular, weak intermolecular forces, not a lot of energy to overcome

Question 32

Which elements have the highest electron affinity?

Answer 32

Group 17 elements have incomplete outer energy levels and a high effective nuclear charge of +7 so attracts electrons the most