A mixture contains elements and/or compounds that
are not chemically joined together. You can use
physical processes to separate them into different
substances
Chromotography- separates liquids of different colours
Distillation- separates liquids with different boiling points
Filteration- separates a solid from
liquid
Pure substances have a sharp melting point. Mixtures have a range of melting points
Filters can be used to separate some
mixtures. They let smaller pieces or liquids
through but trap bigger pieces or insoluble
substances
Inks, paints and foods often contain mixtures of
coloured compounds. Chromatography is used to
find out which coloured compounds a mixture
contains
Rf value
Rf stands for retention factor. We can work out the Rf
value using this equation
Rf- Distance moved by the spot/ Distance moved by the solvent
Distillation
Distillation can be used to separate compounds with
different boiling points. This includes a liquid from
dissolved solids and different liquids
Simple distillation evaporates the solvent away leaving the solute. The vapour is then
condensed and collested
Atomic
structure
Protons have a positive charge
Neutrons have no charge at all
Electrons have a negative charge
Atoms in element always
have equal numbers of
protons and electrons
and so have no overall
charge, because charges
cancel each other out
Isotopes- More atoms
of the same element,
they have the same
atomic number but
have different mass
nuber
Top number is the mass number. And
the bottom number is the atomic
number.