Ionic compounds are composed of positive and negative ions in ratios that balance the charges. They form crystalline lattices with ions arranged in an orderly pattern. The ions are held together by strong electrostatic forces called lattice energy. Ionic compounds have high melting and boiling points, are hard and brittle, and conduct electricity when molten or dissolved but not in the solid state. Polyatomic ions are charged groups of covalently bonded atoms that behave as single ions in ionic compounds.

1. Ionic bonds and ionic compoundsChapter 6.3

2. ObjectivesCompare and contrast a chemical formula for a molecular compound with one for an ionic compoundDiscuss the arrangements of ions in crystalsDefine lattice energy and explain its significanceList and compare the distinctive properties of ionic and molecular compoundsWrite the Lewis structure for a polyatomic ion given the identity of the atoms combined and other appropriate information

3. Ionic CompoundsDefined as : compound composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal.Sodium ChlorideMost ionic compounds exist as

4. 3-D network of positive and negative ions mutually attracted to one another.

5. Above – Na+1 and Cl-1 are in a 1 to 1 ratio

6. Chemical formula is simply written as NaCl.Formula UnitDefined as : the simplest collection of atoms from which an ionic compound’s formula can be established.Calcium FluoridePotassium chlorideCl1 to 1 ratio1 to 2 ratioKRatio depends on charges of ions!KClCaF2

7. Formation of Ionic compoundsUsing electron dot notation to show ionic bonding Na ClSodium atom Chlorine atomNa + Cl Na+1 + Cl -1Sodium atom Chlorine atom Sodium cation Chlorine anionCa + F + F Ca+2 + F -1 + F -1Sodium atom Fluorine atom Fluorine atom Calcium cation Fluorine anion Fluorine anion

8. Characteristics of Ionic BondingIonic crystal has minimum potential energyCrystal Latticeis formedOrderly arrangement of ions Lattice energy