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Elements, Mixtures &
Compounds
What you should know.
- The elements can arranged
in the periodic table.
- The columns of elements
are called groups.
- The rows of elements are
called periods.
- Atoms contain equal
numbers of positive and negative charges. The positive charges are carried
on tiny particles called protons.
- All atoms of the same
element have the same number of protons.
- Elements contain one type
of atom only.
- Compounds contain 2 or
more different types of atom.
- The masses of each
element in a compound are always in the same proportion.
- The chemical formula of a
compound shows the numbers of type of atom present.
- The composition of a
mixture can vary.
- Igneous rocks form from
magma (molten rock). If the magma cools quickly it forms small crystals. If
it cools slowly large crystals are formed.
- Sedimentary rocks are
formed from particles which settle in layers.
- Metamorphic rocks have
been subjected to great heat and pressure.
- Rocks are worn away
(weathered) by wind, rain and ice.
- As particles of rock are
carried along by wind or rivers they wear away more rock. This is called
erosion.
The periodic table is simply a table containing all the
elements. An element contains only one kind of atom. The elements are arranged
in order of the number of protons they contain (Atomic Number). They are also
arranged according to how many electrons are in their outer shell. The table is
arranged in groups (vertical) and periods (horizontal).
Elements in the same group show similar properties to
each other although trends in their reactivity becoming weaker or stronger can
be seen up and down a group. Example:- Lithium, Sodium and Potassium all behave
in a similar way when reacting, but they get progressively more reactive as you
go down the group; so potassium is more reactive than sodium which is more
reactive than lithium!
What you should be able to do.
- Arrange elements into
groups according to their properties.
- Make new compounds.
- Plan how to get copper
from copper sulphate.
- Find the proportion of
magnesium and oxygen in magnesium oxide.
- Separate a mixture of
iron, salt and sand.
- Describe how igneous,
sedimentary and metamorphic rocks are formed.
- Investigate the
weathering of rocks.
- Divide the periodic table
into metals and non-metals.
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