Naming and Formula Writing IONIC COMPOUNDS Naming and Formula Writing

Predicting Charges on Monatomic Ions KNOW THESE !!!! +1 +2 -3 -2 -1 0 Cd+2

Naming Positive Ions Before you name an Ion you have to know the charge. Group 1 = always +1 Group 2 = always +2 Aluminum = always +3 Zinc and Cadmium = always +2 Silver = always +1

The Other Metals All other metals can have various positive charges from +1 to +7 Roman Numerals are used to tell the charge

Monatomic Ions

Naming Postive Ions With group 1, 2, Al, Zn, Cd, and Ag you just give the name of the atom Na+ is Sodium Mg+2 is Magnesium Ag+ is Silver Al+3 is Aluminum

All the other metals With all other metals you give the name Metal followed by a roman numerial Cu+ - Copper (I) Cu+2 – Copper (II) Fe+2 – Iron (II) Fe+3 – Iron (III) U+6 – Uranium (VI)

Naming negative ions All negative ions have their endings changed to –ide Oxygen becomes oxide Fluorine becomes Fluoride Nitrogen becomes Nitride Chlorine becomes Chloride

Names of other Negative Ions Carbide = what you want your parents to do for you Boride = what happened at the rodeo Silicide = what you are seeing right now Fluoride = a state in the union Iodide = Very sad, I guess we will have to Barium.

Writing a Formula Write the formula for the ionic compound that will form between Ba2+ and Cl. To cancel out Ba’s +2, then two -1 Cl’s are needed. Solution: 1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the negative ion Ba2+ Cl Cl 3. Write the number of ions needed as subscripts BaCl2

Balancing a formula by math Every ionic compound should have a formula that has a charge that equals zero. Barium Fluoride Ba+2 F- How many F’s are needed to balance Ba+2 ? Two Formula is BaF2

Another way – Drop, Swap, Reduce Aluminum Oxide Al is always +3 Oxide is always -2 Al+3, O-2 DROP: Al3O2 SWAP: Al2O3 REDUCE: 2 and 3 are lowest integers, so leave alone

Another example Magnesium Oxide Mg is +2 Oxide is -2 Mg+2, O-2 DROP: Mg2O2 SWAP: Mg2O2 REDUCE: MgO, 2 and 2 divide each other out.

Learning Check Write the correct formula for the compounds containing the following ions: 1. Na+, S2- a) NaS b) Na2S c) NaS2 2. Al3+, Cl- a) AlCl3 b) AlCl c) Al3Cl 3. Mg2+, N3- a) MgN b) Mg2N3 c) Mg3N2

Solution 1. Na+, S2- b) Na2S 2. Al3+, Cl- a) AlCl3 3. Mg2+, N3- c) Mg3N2

CaCl2 = calcium chloride Naming Compounds Binary Ionic Compounds: 1. Cation first, then anion 2. Monatomic cation = name of the element Ca2+ = calcium ion 3. Monatomic anion = root + -ide Cl- = chloride CaCl2 = calcium chloride

Naming Binary Ionic Compounds Examples: NaCl ZnI2 Al2O3 sodium chloride zinc iodide aluminum oxide

Learning Check Complete the names of the following binary compounds: Na3N sodium ________________ KBr potassium ________________ Al2O3 aluminum ________________ MgS _________________________

Transition Metals Elements that can have more than one possible charge MUST have a Roman Numeral to indicate the charge on the individual ion. 1+ or 2+ 2+ or 3+ Cu+, Cu2+ Fe2+, Fe3+ copper(I) ion iron(II) ion copper (II) ion iron(III) ion

Learning Check Complete the names of the following binary compounds with variable metal ions: FeBr2 iron (_____) bromide CuCl copper (_____) chloride SnO2 ___(_____ ) ______________ Fe2O3 ________________________ Hg2S ________________________

Polyatomic Ions Some ions are composed of more than one atom. These are called polyatomic ions Poly = more

Formulas and names Nitrate = NO3- Sulfate = SO4-2 Silver nitrate Ag+ NO3- DSR = AgNO3 Copper (I) Sulfate Cu+ SO4-2 Cu2SO4

More Polyatomics Lead (IV) Phosphate Pb+4 PO4-3 Pb3(PO4)4 Notice: When more than one Polyatomic is present you surround it with () Big: The subscripts on Polyatomic ions are NEVER changed.

Learning Check Write the correct formula for the compounds containing the following ions: 1. Na+, PO4-3 a) NaPO4 b) Na2PO4 c) Na3PO4 2. Al3+, NO3- a) Al(NO3)3 b) AlNO3 c) Al3NO3 3. NH4+, N3- a) NH4N b) NH4N c) (NH4)3N

Answers 1. Na+, PO4-3 c) Na3PO4 2. Al3+, NO3- 3. NH4+, N3- a) Al(NO3)3 c) (NH4)3N

More on Polyatomics Most polyatomic ions end in –ate. The ending –ite means one less oxygen is present then in the ending –ate. Example: Nitrate versus Nitrite: NO3- NO2- NOTICE: Only the number of O’s changed, not the charge.

Even More The Prefix Hypo means two less oxygen’s are present then in –ate. Example: Hyposulfite: SO2-2 The Prefix Per- means one extra oxygen is present then in –ate. Examples: Perchlorate ClO4- Chlorate ClO3- Chlorite ClO2- HypoChlorite ClO-

Properties of Ionic Compounds Ionic compounds are: also known as salts They are usually hard and brittle Conduct electricity when molten or dissolved Have very high melting and boiling points Most are soluble in water Normally composed of at least one metal and one nonmetal