Chemical Bonding – Ionic Bonds Part 2

Naming Ionic Compounds Ionic compounds all have two-word names The first word in the name is the same as the name of the first ion (for example, sodium, ammonium, potassium, etc) The second word in the name is either: 1. If the second ion is polyatomic, it is just the name of the polyatomic ion 2. If the second ion is an element, the end of the element’s name changes to –ide Example: chlorine  chloride oxygen  oxide If the metal ion is transition metal, you MUST include the charge on the transition metal in parenthesis between the two words

Practice Naming Ionic Compounds Na2CO3 -- CaSO4 -- KBr -- MgS -- BeCl2 -- NH4F – CuF CuCl2

Writing Ionic Compounds From Name If I have an ionic compound, for example, potassium sulfate, how do I know what the formula is? REMEMBER THAT THE COMPOUND MUST BE NEUTRAL So, I have Potassium, K, which will lose 1 electron and gain a positive charge, making it K+ And, I have Sulfate, a polyatomic ion, which has a charge of -2 Therefore, I need 2 potassium ions to balance out my one sulfate ion, making my formula, K2SO4 -- this is why we have subscripts in chemistry

What About. . . What if I have to put multiple polyatomic ions in a compound, for example, magnesium nitrate? Magnesium has a charge of +2 Nitrate is polyatomic and has a charge of -1 Therefore, we need 2 nitrate ions for each magnesium In this case, we put the entire polyatomic ion in parenthesis and put the subscript outside the parenthesis Our answer would be Mg(NO3)2

Practice Writing Formulas Write the formulas for the following compounds: Calcium phosphate -- Lithium oxide -- Zinc (I) sulfate --

Properties of Ionic Compounds Ionic compounds have the following properties: Crystal Pattern – every ion is attracted to all other ions with the opposite charge -- this results in a repeating 3-dimensional crystal pattern

Properties of Ionic Compounds cont’d High Melting Point – the attraction in the crystal pattern leads to very strong bonds, making it hard to break apart ionic compounds -- ionic compounds melt at high temperatures Conductivity – when dissolved in water, ionic compounds conduct electricity -- in water, the bonds dissociate (fall apart), leaving lots of ions to carry charge Solid ionic compounds do not conduct electricity very well -- melted ionic compounds do conduct electricity fairly well