Chemistry Paper 2 IGCSE

What is a ion

An electrically charged atom or group of atoms (by gaining or losing electrons)

What are negative ions called

Anions

What are positive ions called

Cations

What charge does a ionic compound have

It has no overall charge

When should you use the swap and drop method

When ions in a ionic compound have the same charge

How are ionic bonds represented

Using dot and cross diagrams

What is a ionic bond

Strong electro static forces of attraction between oppositely charged ions

What do thousands of opposite ions in a ionic compound form

Giant ionic lattice

Why do ionic compounds have high melting and boiling points

1. Giant ionic lattice

2. Strong electrostatic forces of attraction between oppositely charged ions

3. Need a lot of energy to overcome

Why are solid ionic compounds poor conductors

1. Ions are in fixed positions

2. So unable to move and carry a charge

What is a covalent bond

Strong electrostatic attraction between shared pair of electrons and the nucleus

Difference between covalent and ionic bonds

In covalent electrons are shared in ionic electrons are donated/taken

What bonds do simple molecular structures have

Covalent bonds (intermolecular forces between neighboring molecules)

Why do simple molecular structures have a low melting and boiling point

1. Weak intermolecular forces between molecules

2. Little energy required to overcome

1 example of a simple molecular structure

C60 fullerene

Can simple molecular structures conduct electricity

No they are used as insulators

2 characteristics of giant covalent structures (giant lattices)

1. Solids

2. High melting points

3. High number of strong covalent bonds

2 examples of giant lattices

1. Diamond

2. Graphite

What is a metallic bond

Strong force of attraction between positive metal ions and delocalised electrons

2 properties of metals

1. High melting and boiling point

2. Conduct electricity

3. Are malleable

What is electric current

The flow of charged particles

When do ionic compounds conduct electricity

When molten

During electrolysis what happens at the anode

Attracts the negatively charged particles

What do aqueous solutions always contain

Water

What happens at the anode in a aqueous solution

Both negatively charged particles are attracted (OH- from the water)

What does OILRIG stand for

Oxidation is loss (of electrons) Reduction is gain (of electrons)

What do half equations display

The loss or gain of electrons

3 steps in investigating electrolysis

1. Add aqueous solution to beaker and cover the electrodes

2. Invert 2 small test tubes to collect gaseous products

3. Connect electrodes to power supply

4. Turn power on for electrolysis

5. Observations of electrodes

6. Gases collected can be identified

Test for hydrogen

Light a splint produces a squeaky pop

Test for oxygen

Relight a glowing splint

What is group 1 known as

Alkali metals

1 similar thing about all group 1 metals

1 electron in their outer shell

Which elements in group 1 react quickest

The ones further down the column

1 observation of all group 1

Moves on the surface

(Li - fizzing

Na - dissolves

K - lilac flame

What are group 7 known as

Halogens

Halogens are

Diatomic

Appearance of halogens

Fluorine - yellow gas

Chlorine - pale yellow/green gas

Bromine - red/brown liquid

Iodine - grey solid

when does a displacement reaction occur

When a more reactive halogen displaces a less reactive halogen

% of nitrogen in the atmosphere

78%

% of oxygen in the atmosphere

21%

% of Argon in the atmosphere

0.9%

% of CO2 in the atmosphere

0.04%

Method to determine % of Oxygen in air

Oxidation of iron

What is combustion

Burning

2 observations of the combustion of magnesium

1. Intense white flame

2. White powder produced

What is thermal decomposition

When breaking down a substance using heat

Observation of thermal decomposition of copper carbonate

Green to black powder

Flame test observation for K (potassium)

Lilac flame

Flame test observation for Li (lithium)

Red flame

Flame test observation for Na (sodium)

Yellow flame

Flame test observation for Cu (Copper)

Green flame

Flame test observation for Ca (Calcium)

Orange flame

2 steps to test for halides

1. Add nitric acid

2. After add silver nitrate

Acronym to remember Halide tests

Can We Buy Candy In Yemen

CWBCIY

Acronym for cation tests

Can Boys Identify Girls in Russia At Ben’s

Describe the test for sulphate ions

1. Add Barium Sulphate

2. Barium Sulphate Solid forms (white)

Describe the test for Carbonate ions

1. Add hydrochloric acid

2. bubble gas through limewater

4 factors affecting rate of reaction

1. Concentration

2. Temperature

3. Surface area

4. Catalyst

Why does increasing concentration affect the rate of reaction

1. More collisions per second

2. So more frequent successful collisions per second

3. So rate of reaction increases

What is a Catalyst

Speeds up the reaction without being used up

What is the difference between energy of reactants and products called

Enthalpy Change

What is the enthalpy change of exothermic reactions

Negative

What is the enthalpy change of endothermic reactions

Positive

What does the initial curve on a energy diagram represent

Activation energy

What do catalysts provide

An alternative pathway with lower activation energy

What is a reversible reaction

When products from a reaction can react with each other to form the initial products

2 examples of reversible reactions

1. Thermal decomposition of ammonium chloride

2. Dehydration of Copper(ll) sulphate

1 condition for dynamic equilibrium

A closed system