Home : Structures : Atomic Structure
Atoms are some of the simplest particles to make up solids, liquids
or gases. The atoms are always moving and may be joined together by special bonds
Atoms are made of three different things: protons, neutrons and electrons.
The protons and neutrons are held together in the centre of the atom to form an object called the nucleus.
The electrons can be found circling the nucleus at different distances from it.
Chemical reactions involve the atom's electrons - mainly because these are on the outside of the atom and are the first thing
that another atom will meet when it reacts with it. Nuclear reactions involve the atom's nucleus and may release large amounts
Each type of atom has a different number of protons, neutrons and electrons. The number of protons and
neutrons affect the mass of the atom - how heavy it is. The number of electrons has a strong influence on how
reactive the atom is.
The number of electrons in the very outside of the atom are the ones that take part in
chemical reactions.The atoms can be arranged in a table so that all the ones with one electron in the outer layer
(or shell) are in the first column. Ones with two electrons are in the second column ... and so on.
This table of atoms is called the periodic table.
When the atoms react many of them try to make sure they get eight electrons in the outermost layer.
So an atom with one electron on the outside (eg. sodium) will react very easily with an atom with seven electrons
(such as chlorine).
In this way, sodium will lose its 'odd' electron and chlorine will end up with eight electrons on the outside - so both
atoms will be happy!