CHEMISTRY PAPER 1 – ATOMIC STRUCTURE
Atoms
All substances are made of atoms. An atom is the smallest part of an
element that can exist.
Conservation of mass
No atoms can be lost or made during chemical reactions. This means
that the mass of products is the same as the mass of the reactants
so equations must be balanced.
Compounds
Formed from elements by chemical reactions. Compounds contain two or
more elements chemically bonded together. They can also be separated
by chemical reactions.
Mixtures
Consists of two or more elements or compounds not chemically joined
together. This means that they have the same chemical properties,
and they can be separated using different separation techniques such
as filtration, crystallisation, distillation, fractional
distillation, and chromatography. These do not involve chemical
reactions.
Crystallisation
This is a separation technique to separate a soluble substance from
a solvent. It can be used to separate salt from water or other
substances that have been dissolved. It involves adding the solution
to an evaporating dish and heating it with a Bunsen burner to get
the water to evaporate. Heating is stopped when crystals begin to
form, and the rest of the water is left to evaporate. To heat the
salt more gently, you can use a water bath which involves placing
the evaporating dish on a beaker of water that is being heated with
a Bunsen burner.
Filtration
a separation technique to separate an insoluble substance from a
solvent. It can be used to separate sand from water or other solids
that have not dissolved. It involves a funnel and filter paper and
pouring solution through the filter paper.
Fractional distillation
Separation technique to separate a mixture of miscible liquids such
as ethanol or water that have different boiling points. It involves
adding the mixture to a round bottom flask connected to a
fractioning column that usually contains glass beads. This is then
fitted to a condenser. The mixture is then heated with a Bunsen
burner to get the liquids to evaporate. The substance with a higher
boiling point will condense more readily and fall back into the
Atoms
All substances are made of atoms. An atom is the smallest part of an
element that can exist.
Conservation of mass
No atoms can be lost or made during chemical reactions. This means
that the mass of products is the same as the mass of the reactants
so equations must be balanced.
Compounds
Formed from elements by chemical reactions. Compounds contain two or
more elements chemically bonded together. They can also be separated
by chemical reactions.
Mixtures
Consists of two or more elements or compounds not chemically joined
together. This means that they have the same chemical properties,
and they can be separated using different separation techniques such
as filtration, crystallisation, distillation, fractional
distillation, and chromatography. These do not involve chemical
reactions.
Crystallisation
This is a separation technique to separate a soluble substance from
a solvent. It can be used to separate salt from water or other
substances that have been dissolved. It involves adding the solution
to an evaporating dish and heating it with a Bunsen burner to get
the water to evaporate. Heating is stopped when crystals begin to
form, and the rest of the water is left to evaporate. To heat the
salt more gently, you can use a water bath which involves placing
the evaporating dish on a beaker of water that is being heated with
a Bunsen burner.
Filtration
a separation technique to separate an insoluble substance from a
solvent. It can be used to separate sand from water or other solids
that have not dissolved. It involves a funnel and filter paper and
pouring solution through the filter paper.
Fractional distillation
Separation technique to separate a mixture of miscible liquids such
as ethanol or water that have different boiling points. It involves
adding the mixture to a round bottom flask connected to a
fractioning column that usually contains glass beads. This is then
fitted to a condenser. The mixture is then heated with a Bunsen
burner to get the liquids to evaporate. The substance with a higher
boiling point will condense more readily and fall back into the
