Metals

Question 1

Structure and bonding of metals

Answer 1

Metals have a giant metallic lattice structure, they contain strong electrostatic forces of attraction between cations and the sea of delocalised electrons.

Question 2

Physical properties of metals

Answer 2

1. High melting/boiling point (except Group 1 and Mercury)
   - metals have giant metallic lattice structures, a high amount of energy is required to overcome the strong electrostatic forces of attraction between the cations and the sea of delocalised electrons.
2. Good conductor of heat and electricity
   - The mobile delocalised electrons can act as mobile charge carriers and conduct heat.
3. Malleable
   Pure metals contain atoms of the same size and are arranged in a regular, orderly manner allowing the layers of atoms to slide over one another easily when a force is applied.
4. High density
   Metals contain giant metallic lattice of closely packed cations. Hence, they have high density as they have a high mass in a given unit volume

Question 3

Alloys

Answer 3

A mixture of a metal with one or more elements

Question 4

Alloys are stronger and harder than pure metal

Answer 4

Size of the atoms of the added element is different in size from the atoms of the parent metals. This disrupt the regular, orderly arrangement of the parent metal atoms, making it more difficult for the layers of atoms to slide over each other.

Question 5

Decomposition of metal carbonates

Answer 5

K,Na: do not decompose (very reactive metals, carbonates are very thermally stable)
Ca-Cu: decompose into metal oxide + CO2
Ag: decompose into silver and CO2

Question 6

Reduction of Metal Oxide with Carbon

Answer 6

K-Al: cannot be reduced by carbon
Zn-Cu: reduced by carbon to form metal + CO2

Question 7

Reduction of metal oxide with hydrogen

Answer 7

K-Zn: cannot be reduced by hydrogen
Fe-Cu: reduced by hydrogen to form metal + steam

Question 8

Why does K-Al use electrolysis in their extraction?

Answer 8

They are highly reactive metals, their compounds are very stable and requires a lot if energy to extract them.

Question 9

Main composition of haematite

Answer 9

Iron (II) oxide and silicon dioxide

Question 10

Blast furnace is lined with refractory materials.

Answer 10

Al2O3 and MGO has high melting points, they can trap heat.

Question 11

Raw materials for extraction of iron

Answer 11

Haematite
Coke
Limestone

Question 12

Key reaction in extraction of iron

Answer 12

Production of carbon dioxide:
C + O2 (from air) -> CO2

Production of carbon monoxide (RA):
CO2 + C -> 2CO

Reduction of haematite by CO:
Fe2O3 + 3 CO -> 2 Fe + 3 CO2

Removal of acidic impurities:
CaCO3-> CaO (base) + CO2
CaO + SiO2 -> CaSiO3(slag, float on top of the molten iron as it is less dense. Used to make roads.)

Question 13

Why are raw iron extracted from the blast furnace not suitable for use?

Answer 13

They are too brittle to be useful as it contain a high percentage of carbon, this iron is converted to mild steel by blowing oxygen through the molten iron to oxidise som of the carbon into carbon dioixde