(Section 2.1)

Bonding – Electrostatic forces of attraction between pairs of atoms or ions. Compounds – Two or more elements that combine to form new substances by a chemical bond. Octet Rule – When bonds form between atoms, the atoms gain, lose, or share electrons in such a way that they create a bond containing 8 electrons ( Exceptions are H, He, Li, Be and B)

(1) Ionic Bond – One or more electrons are transferred from a metal to a nonmetal. This results in an electrostatic attraction between a positive particle and a negative particle.  The result is the formation of two ions.  The positive ion is known as the cation.  The negative ion is known as the anion.

 Ionic bonds are fairly strong and most ionic compounds (also known as ionic salts) are solid at room temperature.  In an ionic crystal, cations and anions are packed together in a regular, repeating pattern.

Cation radius is usually smaller than the radius of the corresponding atom. WHY?  The cation loses its valence electrons when it is formed which means all outer electrons are removed (it loses its outer shell).

Anion radius is usually larger than the radius of the corresponding atom. WHY?  The addition of more electrons results in more electrostatic repulsion between the outermost electrons (so, they spread out!)

 Ionic crystals are brittle.  Relatively high melting and boiling points.  Melting ionic compounds or dissolving them in water will enable ionic compounds to conduct electricity. Ionic compounds are electrolytes.

Formula Unit – The smallest unit of an ionic compound that still has properties of that compound. Ex. NaCl, CaCl 2, LiF