Chemical Bonding
Electron Configuration
In the periodic table,
elements are arranged in a specific order.

The number of electrons increases by one from left to right across a period. 

Atoms with a complete outer energy level are stable.  Elements in group 18 are stable.

Neon is stable with 8 electrons in its outer level.
Chemical Bonds
A chemical bond is the force that holds two atoms together. 

Atoms bond with other atoms in such a way that each atom becomes more stable, by having filled outer energy levels.
Ionic Bonds
When one atom gives up an electron 
to another atom, the bond between 
them is an ionic bond. 
The atom that donates electrons 
becomes a positive ion. The atom 
that receives electrons becomes a 
negative ion. 
Ionic bonds form between 
metals and non-metals.

Covalent Bonds
A covalent bond is formed when one atom shares one or more electrons with another atom. No ions are formed.

Covalent bonds form between two non-metals.

Molecules
When atoms share electrons, they stick together to become part of a molecule. 
Compounds are substances made of more than one type of atom. The smallest piece of a compound formed by covalent bonds is a molecule.