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1-Pure Substances: Elements
A pure substance is matter that has one kind
of atom or molecule through-out the whole substance. The difference
between a pure substance and a mixture
(mechanical, suspension or solution) is in the atoms/molecules. For a mechanical mixture, the atoms/molecules
are completely separate and can be seen by the unaided eye. For a suspension,
the atoms/molecules
are more mixed together, but are still separate (no new compounds are formed).
For a solution, the atoms/molecules
look like there is a new compound, but when you break it down under a magnifying
glass, there are two or more separate atoms/molecules. This is not a pure substance.
Elements:
There are more than a million pure substances, all with the same 100 atoms making up the molecules.
Each of those 100 elements has their own atoms
that share the same name. Some elements do not appear in nature and are laboratory
based, but are extremely dangerous and radioactive, like Einsteinium. Some
are very common like hydrogen, copper and silicon, while others are do appear
in nature, but are very rare, such as krypton. Others are poisonous to people,
like lead, mercury and chlorine, while even more are necessary for life, like
oxygen. When two elements combine completely, and the atoms
join together to form molecules,
a compound
is formed. Below is an image of the element mercury.