Chemistry Paper 1 - Atoms, Elements, Compounds & Mixtures

What are all substances made up of?

Atoms

How many atoms do an element contain?

Contains 1 Atom

How many different elements are there?

100 Different Elements

What is a compound?

A substance which contains atoms of 2 or more elements chemically combined together in fixed proportions.

What are compounds represented by?

Chemical Formula

Which have a larger mass? Reactants or Products

They both have the same mass, because no atoms can be lost or made.

What are mixtures?

Two or more elements or compounds not chemically combined together.

What are the five ways that mixtures can be separated?

• Filtration

• Crystallisation

• Simple distillation

• Fractional Distillation

• Chromatography

What is filtration used for?

To separate soluble solids from insoluble solids.

Explain how filtration works.

• Dissolve the soluble solid in water.

• Use filter paper to separate the insoluble solids from the mixture.

What is crystallisation used for?

To obtain a soluble solid from a solution.

Explain how crystallisation works.

• Gently heat the mixture.

• Water evaporates from the mixture.

• Leaving behind crystals of the solid.

What is simple distillation used for?

Obtain a solvent from a solution.

Explain how simple distillation works.

• Solution is heated

• Solvent vapour leaves the solution

• It moves away and cools and condenses

• The remaining solution becomes more concentrated as there is less solvent

What is fractional distillation used for?

To separate mixtures in which components have different boiling points.

Explain how fractional distillation works.

Vapour rises through a column which is hot at the bottom and cooler at the top.

Vapours condense when they reach a part of the column where temperature is lower than their boiling point.

Each liquid in the mixture is led away from the column

What is chromatography used for?

To separate the different soluble coloured components of a mixture.

Explain how chromatography works.

Ink or plant dye is dotted along the pencil line.

Paper is lowered into a solvent, and some dye spreads up the paper.

Different substances travel at different rates, meaning the colours seperate