CHEMICAL BONDS

IONIC BONDS  Form when electrons are completely transferred from one atom to another. Atoms are electrically neutral.  Charged particles are called ions. (negatively charged ions are called anions.) (positively charged ions are called cations.)

Typical Example of Ionic Bond  Sodium chloride  Na + Cl Na+ + Cl -  Because these bonds can either transfer or share their valence electrons(or one or more atoms lose electrons and other atoms gain them), the sodium (Na) contributes the electron to the chloride (Cl), leaving it with a closed shell.

COVALENT BONDS  These bonds occur when molecules in which atoms share electrons, or covalent molecules, bonds.  EX: hydrogen, that has one electron, can become stable when sharing electrons  A hydrogen atom may also share its electron with an atom of a different element.  Polar molecules- a molecule with 2 charged poles  Occurs when the electron pairs in a molecule are not shared equally and spend more time in the vicinity of the oxygen atom. The end of the molecule then becomes slightly more negative on one end.