ELEMENTS AND COMPOUNDS SUMMARY
There are 118 different elements which each have their own chemical symbol. Atoms of
different elements can be combined to make compounds.
ATOM – the smallest possible unit of an element. A positive nucleus surrounded by orbiting
negative electrons.
COMPOUND – made up of at least two different elements chemically bonded together
MIXTURE - made up of two or more substances (elements or compounds) which have not
been chemically combined.
The individual properties of the substances within the mixture do not change as
there has not been a chemical reaction.
Key features of a chemical reaction
- Compounds are broken or formed
- At least one new substance is created
- There is a measurable energy change
- No atoms are created or destroyed
A chemical reaction is written in the format: reactants products
It can contain just words (a word equation) or symbols (a symbol equation should be
balanced).
Separating mixtures;
CHROMATOGRAPHY – separates solutions with a different number of solutes within the
solvent.
Equipment
Chromatography paper
Beaker
Solute (e.g water or acid)
Wooden spill
Method
Place a drop of the solution to be separated near the bottom of a piece of
chromatography paper.
Dip the very bottom of the paper into a soluble solution.
The solvent moves up the paper and carries the solute with it.
Different solutes move at different speeds, so they separate on the paper.
CRYSTALLISATION – separates solutions into their parts: the dissolved solute and the
solvent.
Equipment
Provider of heat (e.g a Bunsen)
Evaporating basin
There are 118 different elements which each have their own chemical symbol. Atoms of
different elements can be combined to make compounds.
ATOM – the smallest possible unit of an element. A positive nucleus surrounded by orbiting
negative electrons.
COMPOUND – made up of at least two different elements chemically bonded together
MIXTURE - made up of two or more substances (elements or compounds) which have not
been chemically combined.
The individual properties of the substances within the mixture do not change as
there has not been a chemical reaction.
Key features of a chemical reaction
- Compounds are broken or formed
- At least one new substance is created
- There is a measurable energy change
- No atoms are created or destroyed
A chemical reaction is written in the format: reactants products
It can contain just words (a word equation) or symbols (a symbol equation should be
balanced).
Separating mixtures;
CHROMATOGRAPHY – separates solutions with a different number of solutes within the
solvent.
Equipment
Chromatography paper
Beaker
Solute (e.g water or acid)
Wooden spill
Method
Place a drop of the solution to be separated near the bottom of a piece of
chromatography paper.
Dip the very bottom of the paper into a soluble solution.
The solvent moves up the paper and carries the solute with it.
Different solutes move at different speeds, so they separate on the paper.
CRYSTALLISATION – separates solutions into their parts: the dissolved solute and the
solvent.
Equipment
Provider of heat (e.g a Bunsen)
Evaporating basin
