1. Ionic Bonds Notes 5-2 Key Ideas: 1. How do ions form bonds? 2. How are the formulas and names of ionic compounds written? 3. What are the properties of ionic compounds?

2. Ions An atom or group of atoms with an electric charge is an ion. How Ions Form Lose a valence electron = gain a positive charge = cation Gain a valence electron = gain a negative charge = anion Polyatomic Ions Ions made of several atoms (more than one) Ammonium ion / 1+ / NH4+ Bicarbonate ion / 1- / HCO3- Ionic Bond (the attraction between two oppositely charged ions) Ionic bonds form as a result of the attraction between positive and negative ions. NA+ Cl- → NaCl A + plus a – equals a NEUTRAL charge!

3. Chemical Formulas and Names

4. 3 Properties of Ionic Compounds Generally, ionic compounds are hard, brittle solids with high melting points. They conduct electricity when melted or dissolved in water. 1. Ionic Crystals Ionic compounds form solids by building up a repeating pattern of ions known as crystals. These crystals have an orderly, three dimensional arrangement. 2. High Melting Points When you hear NaCl, its energy increases and the ionic crystal melts into a liquid. A lot of energy is needed to break the bonds therefore, ionic compounds have high melting points. (For NaCl the melting point is 801C.) 3. Electrical Conductivity Ionic compounds dissolved in water conduct electricity. Ionic compounds dissolved due to melting into a liquid conduct electricity. Ionic compounds in a solid do NOT conduct electricity well because the ions are so tightly bound together.