Material Chemistry:Atoms and Their Electrons
Atoms are made of three principal particles. Extremely tiny electrons move in a cloud around the outside. They have a negative charge. Inside is the nucleus which is made up of protons and neutrons. The neutrons have no charge and the protons are positively charged. The charge on a proton exactly balances the electrons negative charge. Most of the atom is space， a complete vacuum. The outermost electrons cause chemical reactions and this is what we are going to examine.
- Added：2006
- Country：Australia
- Duration：34
- Time of update：2011/8/16 14:32:14