An '''atom''' [http://dictionary.reference.com/browse/atom (Def:Atom)] is the basic building block of all matter and is composed of 3 principle subatomic particles: '''protons''', '''neutrons''' and '''electrons'''. The most common form of Hydrogen, called Protium, has only one proton and one electron. Atoms of every other element are made up of a combination of these 3 elementary particles, protons, electrons and neutrons. | An '''atom''' [http://dictionary.reference.com/browse/atom (Def:Atom)] is the basic building block of all matter and is composed of 3 principle subatomic particles: '''protons''', '''neutrons''' and '''electrons'''. The most common form of Hydrogen, called Protium, has only one proton and one electron. Atoms of every other element are made up of a combination of these 3 elementary particles, protons, electrons and neutrons. |