Periodicity

Question 0

Info on silicon

Answer 0

A semi-metal (metalloid), conducts electricity to some extent

Question 1

Info on sodium, magnesium and aluminium

Answer 1

Shiny, conduct electricity and react with dilute acids to give hydrogen and salts

Question 2

What is a metalloid

Answer 2

A semi-metal

Question 3

What is another name for a semi-metal

Answer 3

A metalloid

Question 4

Info on phosphorus, sulphur and chlorine

Answer 4

Non-metals, don’t conduct electricity, have low melting and boiling points

Question 5

Info on argon

Answer 5

Noble gas, chemically unreactive, exists as separate atoms

Question 6

Which 3 elements in period 3 react with water

Answer 6

Sodium, magnesium and chlorine. Reaction with sodium is vigorous, sodium floats on surface of water and fizzes rapidly, melting because of the heat given out by the reaction, strong alkaline solution of sodium hydroxide formed (pH 12-14). Reaction with magnesium very slow at room temp, resulting solution less alkaline (pH 9-10) as magnesium hydroxide is sparingly soluble meaning only a few hydroxide ions are produced.Reaction is much faster with heated magnesium and steam and gives magnesium oxide and hydrogen

Question 7

Period 3 elements react with oxygen in which type of reaction

Answer 7

Exothermic reaction

Question 8

Reaction of sodium and oxygen

Answer 8

Burns brightly with yellow flame to form white sodium oxide

Question 9

Reaction of magnesium and oxygen

Answer 9

Strip of magnesium ribbon burns with bright white flame, forms white powdered magnesium oxide. White fumes given off. Magnesium is oxidised and oxygen is reduced

Question 10

Reaction of aluminium and oxygen

Answer 10

Aluminium powder heated then lowered into a gas jar of oxygen, burns brightly to give aluminium oxide, a white powder. Aluminium= reactive metal, always coated with a strongly bonded surface layer of oxide which protects from further reaction. Means it can be used for everyday purposes saucepans, window frames etc. if surface scratched the exposed aluminium reacts rapidly with air and seals off surface

Question 11

Reaction of silicon and oxygen

Answer 11

Forms silicon dioxide

Question 12

Reaction of phosphorus and oxygen

Answer 12

Red phosphorus must be heated before it will react with oxygen. White phosphorus spontaneously ignites in air and white smoke of phosphorus pentoxide given off. Red and white phosphorus allotropes of phosphorus, same element with atoms arranged differently. If supply of oxygen is limited phosphorus trioxide is also formed

Question 13

What are allotropes

Answer 13

The same element with the atoms arranged differently

Question 14

Example of allotropes

Answer 14

Red and white phosphorus

Question 15

Reaction of sulphur and oxygen

Answer 15

Sulphur powder heated, lowered into gas jar of oxygen, burns with blue flame to form colourless gas sulphur dioxide (and a little sulphur trioxide also forms). Misty, choking fumes of sulphur dioxide given off

Question 16

Metal oxides structure

Answer 16

Form giant ionic lattices where bonding extends throughout compound, resulting in high melting points. The bonding in aluminium oxide is ionic but has some covalent character as aluminium forms very small ion with large positive charge so can approach the oxygen ions closely and distort its electron cloud

Question 17

Non-metal oxides structure

Answer 17

Silicon dioxide has giant covalent structure, bonding extends through giant structure, high melting point due to strong covalent bonds. Phosphorus and sulphur oxides exist as separate covalently bonded molecules (simple molecular). Phosphorus oxides are solids, intermolecular forces are weak Vdw and dipole-dipole forces, melting points low

Question 18

Which 2 oxides are insoluble in water

Answer 18

Aluminium oxide

Silicon dioxide

Question 19

Why is sodium more reactive than magnesium

Answer 19

It takes less energy to lose one electron than it does to lose 2. So more energy is needed for magnesium to react

Question 20

What is the pH of NaOH

Answer 20

14

Question 21

What is the pH of H3PO4

Answer 21

1-2

Question 22

Predict whether the melting point of lithium oxide is higher than, equal to or lower than the melting point of sodium oxide. Explain

Answer 22

Higher, the Li+ ion is smaller than the Na+ ion. It attracts the O2- group more strongly

Question 23

Explain why sodium oxide reacts to form an alkaline solution when added to water

Answer 23

Basic oxide, the oxide ions (O2-) reacts with water forming OH- ions (NaOH formed)

Question 24

Suggest one reason why a thin layer of aluminium oxide protects aluminium from corrosion in moist air

Answer 24

It is insoluble in water