2 Review!Ion – atom that is no longer neutral because it has lost or gained electronsNow it has an electric charge!Atoms with 5, 6 or 7 valence e- become more stable when that number increases to 8.Atoms with 1, 2 or 3 valence electrons can become more stable when they lose electrons.Lose e- become positive ionGain e- become negative ion
3 Ions and Their Charges What does this chart mean?! NameChargeSymbol or FomulaLithium1+Li+SodiumNa+PotassiumK+AmmoniumNH4+Calcium2+Ca2+MagnesiumMg2+Aluminum3+Al3+Fluoride1-F-ChlorideCL-IodideI-BicarbonateHCO3-NitrateNO3-Oxide2-O2-FsulfideS2-CarbonateCO32-SulfateSO42-Phosphate3-PO43-What does this chart mean?!How does Li have a +1 charge?How does Aluminum have a +3 charge?Notice how the names of F, Cl, and I have changed? Why?
4 Polyatomic IonsPolyatomic Ions – Ions that are made of more than one atom.AmmoniumBicarbonateGroup of atoms that reacts as a unitHave overall positive or negative charge
5 Ionic Bonds The attraction between two oppositely charged ions Form as a result of positive and negative ions being attracted to each other.Form ionic compounds!Usually form between a metal and nonmetal!
6 The chemical formula for the compound reflects this balance. When ionic compounds form, ions bond in a way that balances out the charges on the ions.The chemical formula for the compound reflects this balance.combination of symbols that shows the ratio of elements in a compound
7 Formulas of Ionic Compounds Subscript - tells you the ratio of elements in the compoundif no subscript – it’s understood to be 1
8 Naming Ionic Compounds The name of the (+) ion comes first, followed by the name of the (-) ion.Positive ion is usually a metal.If the negative ion is a single element,end of it’s name changes to –ide.NaCl Sodium ChlorideMgO Magnesium Oxide
9 If the negative ion is polyatomic: Ends with -ate or -iteNH4NO3 ammonium nitrate (fertilizer)
10 Ionic Crystals Form solids by building up repeating patterns of ions. Have orderly, three dimensional arrangement called a crystal.Every ion is attracted to ions of opposite charge that surround it.Many crystals are hard and brittle, due to the strength of their ionic bonds
11 High Melting PointsWhen ions have enough energy to overcome the attractive forces between them, they break away from each other.Crystal melts into liquidA lot of energy is needed to break these bonds
12 Electrical Conductivity When ionic crystals dissolve in water, the bonds between ions are broken.Ions are free to move about & the solution conducts current.Solids do not conduct current well good insulators