• Neutrons keep the protons from flying away from each other

• They make the nucleus more stable

• Every element has a proton:neutron ratio that is the most stable

Neutrons

• Atoms can bind together to form molecules

• The electrons make that possible by either:

  • Moving from one atom to another

  • Being shared between atoms

Electrons

• An ion is an atom that has either a positive or negative charge

• It has to either gain, or lose, electrons

Ions

An atom becomes:

• a Cation if it loses electrons (and becomes positive)

• an Anion if it gains electrons (and becomes negative)

Cations and Anions

• When an electron transfers (or moves) from one atom to another, two ions form

  • One is positive and the other is negative

• They become attracted to each other and form an ionic bond

Ionic Bonds

• In a covalent bond, the electrons are shared between two atoms

• They don't move from one atom to another

• The shared electrons hold the two atoms together

Covalent Bonds