C7: strategies of answering questions

Question 1

What are the 3 parts to answer when faced with properties-related questions?

Answer 1

1. The type of bonding present
2. Structure
3. ANSWER the question directly explaining how the physical property can be explained using the
   bonding and particles present

Question 2

Ionic substances, e.g. NaCl, MgCl2
Property: Non-conductors of electricity when solid
Explanation: ?

Answer 2

Ions firmly bound in the lattice and electrons are localised
in the ions, so there are no mobile charged particles

Question 3

Ionic substances, e.g. NaCl, MgCl2
Property: Conductors of electricity when molten or solution
Explanation: ?

Answer 3

Ions free to move

Question 4

Ionic substances, e.g. NaCl, MgCl2
Property: High MP and BP
Explanation: ?

Answer 4

Strong ionic bonding extending throughout the lattice

Question 5

Ionic substances, e.g. NaCl, MgCl2
Property: Hard
Explanation: ?

Answer 5

Ions strongly bound in the lattice

Question 6

Ionic substances, e.g. NaCl, MgCl2
Property: Brittle
Explanation: ?

Answer 6

Distortion causes repulsion between ions of like charge

Question 7

Covalent molecular substances
Property: Non-conductors of electricity unless a reaction occurs with water to produce ions
Explanation: ?

Answer 7

The molecules are uncharged and the electrons are localised
in covalent bonds and not free to move

Question 8

Covalent molecular substances
Property: low MP and BP
Explanation: ?

Answer 8

Weak forces between molecules

Question 9

Covalent molecular substances
Property: Soft solids, liquids or gases
Explanation: ?

Answer 9

Weak forces between molecules

Question 10

Covalent network substances, e.g. carbon allotropes & SiO2
Property: Non-conductors when soild or molten
Explanation: ?

Answer 10

Electrons localised in covalent bonds and there are no ions

Question 11

Covalent network substances, e.g. carbon allotropes & SiO2
Property: Very high MP
Explanation: ?

Answer 11

Strong covalent bonding extending throughout the network

Question 12

Covalent network substances, e.g. carbon allotropes & SiO2
Property: Hard
Explanation: ?

Answer 12

Atoms strongly bound within the network

Question 13

Covalent network substances, e.g. carbon allotropes & SiO2
Property: Brittle
Explanation: ?

Answer 13

Distortion breaks the covalent bonds

Question 14

Metallic substances, e.g. Al, Mg, Na, Fe
Property: Good conductor of electricity and heat
Explanation: ?

Answer 14

Delocalised electrons transfer charge and thermal energy

Question 15

Metallic substances, e.g. Al, Mg, Na, Fe
Property: High MP and BP
Explanation: ?

Answer 15

Strong metallic bonding extending throughout the crystals

Question 16

Metallic substances, e.g. Al, Mg, Na, Fe
Property: Dense
Explanation: ?

Answer 16

Ions tightly packed in the crystals

Question 17

Metallic substances, e.g. Al, Mg, Na, Fe
Property: Malleable and ductile
Explanation: ?

Answer 17

Distortion does not distrupt the metallic bonding

Question 18

Metallic substances, e.g. Al, Mg, Na, Fe
Property: Lustrous
Explanation: ?

Answer 18

Regular crystal structure cause reflection of light