Atomic Structure Catch-up

Atomic Structure Revision
Atom - is the smallest structure of an element which cannot be broken by any chemical
means. A typical atom consists of a three sub-atomic particles (a nucleus of protons
(+) and neutrons (0) with electrons (-) orbiting this
Element – When atoms are all of the same type (They
have the same number of protons).
Compound – Two or more different atoms joined
Molecule – Two or more atoms joined together (Can
be elements or compounds).
Periodic Table – The table of elements arranged in
order of atomic number so that elements with similar
properties are in the same column (you should have
one of these already).
Chemical Symbol – Is the code for an element found in the periodic table. Only the first
letter is capitalised (eg. ‘He’ is the symbol for Helium).
Nucleus – is the centre of an atom and where most of an atoms mass comes from. It contains
both protons and neutrons and is positively (+) charged.
Proton – is a positively (+) charged sub-atomic particle with mass, found within the nucleus
of the atom. The number of protons will tell you the Atomic Number of an element.
Neutron – has a neutral (0) charge and is a sub-atomic particle with mass, found within the
nucleus of the atom. The number of neutrons + protons = Atomic Mass of an element.
Electron – is a tiny, negatively (-) charged sub-atomic particle, with almost no mass, found
outside of the nucleus. In a neutral atom the number of electrons (-) and protons (+) is
usually the same.
Atomic Number – The number of
protons in the nucleus of an atom,
which determines the chemical
properties of an element and its place
in the periodic table.
Atomic Mass – Is approximately
equivalent to the number of protons +
neutrons in an atom. It is usually
found underneath the chemical symbol
on the periodic table.
Protons = Atomic Number = Element
Neutrons + Protons = Atomic Mass
Number of Electrons (-) = Number of Protons (+) in a neutral atom