Protons are positively charged.
Neutrons have no charge.
Electrons are negatively charged.
The Periodic Table
Atoms are represented by symbols.
Vertical columns are called groups.
Elements in a group all have
the same number of
electrons in their outer shell.
Electron Shells
Electrons move around the Nucleus.
They occupy shells. The first shell has
a maximum of 2 electrons, whilst the
rest have a maximum of 8.
In most atoms (other than the
Noble Gases), the outer shell isn't
full, which makes them want to
react to fill it.
Compounds
Atoms join
together to
make
compounds.
A compound formed using a metal and a
non-metal are bonded using ionic bonding
as they from ions. The one that loses
becoms a positive ion. The one that gains
becomes a negative ion.
A compound formed from non-metals consists of molecules.
Each atom shares an electron with another atom. This is
covalent bonding.
The properties of compounds are
completely different.
The formula shows what
atoms are in a compound.
CO2 is a compound
containing 1 Carbon atom
and 2 Oxygen atoms.