Nomenclature

Ions: an atom or group of atoms with a positive or negative charge Cation: an ion with a positive charge because electrons were lost (name the same as the element) Anion: an ion with a negative charge because electrons were gained (name ending changes to “-ide”)

Cation Formation Sodium Atom Sodium Ion 1 e- 8 e- 2 e- 8 e- 2 e- 11 p+

Anion Formation Fluorine Atom Fluoride Ion 9 p+ 10 n0 9 p+ 10 n0 1 e-

Metal Ions Many transition metals have more than one type of ion Transition metals with more than one type of ion are named using Roman numerals Fe+2 is Iron (II) Fe+3 is Iron (III) Transition metals with only one ion are simply given the name of the cation Silver is Ag+1 Cadmium is Cd+2 Zinc is Zn+2

Polyatomic Ions H O - H H - N - H H A tightly bound group of atoms that acts as a unit and carries a charge Names usually end in “-ate” or “-ite” Has 8 electrons but should have 9 (5 from N and 4 from H), so there is one less electron than expected. +1 H -1 O - H H - N - H H Has 8 electrons, but it should have 7 (6 from O and 1 from H), so there is an extra negative charge.

Most used Polyatomic Ions: Acetate Chlorate Cyanide Hydroxide Nitrate Nitrite Carbonate Sulfate Sulfite Phosphate Ammonium

Criss-Cross Method Do not write the charge (the + or -) Do not write a subscript of 1 (H2O, NOT H2O1) Parenthesis MUST be used when a subscript is added to a polyatomic ion [Mg(OH)2, NOT MgOH2] Subscripts MUST be in the lowest, whole-number ratio

Fe+3 O-2 Fe2O3 Ca+2 NO 3 -1 Ca(NO3)2 Fe+2 O-2 Fe2O2 FeO Pb+4 O-2 Pb2O4 PbO2

Naming Ionic Compounds Name the cation first Name the anion second (end in “-ide”) If the metal has more than one charge, use the Roman numeral to match the charge If a polyatomic is present, look it up on your chart Fe2O3 Iron (III) oxide Mg(OH)2 Magnesium hydroxide LiOH Lithium hydroxide FeO Iron (II) oxide PbO2 Lead (IV) oxide

Naming Acids Acids always begin with the element hydrogen. You need to become familiar the following acids: Hydrochloric Acid: HCl Hydrofluoric Acid: HF Hydrobromic Acid: HBr Hydroiodic Acid: HI Nitric Acid: HNO3 Acetic Acid: HC2H3O2 Sulfuric Acid: H2SO4 Carbonic Acid: H2CO3 Phosphoric Acid: H3PO4

Naming Molecular Compounds Use prefixes: 1 = mono 2 = di 3 = tri 4 = tetra 5 = penta 6 = hexa 7 = hepta 8 = octa 9 = nona 10 = deca Never use the prefix “mono” with the first element (carbon monoxide) The ending of the second element will be “-ide” CO2 PCl5 H2O Carbon dioxide Phosphorus pentachloride Dihydrogen monoxide

Writing Formulas From Names Are the elements 2 non-metals? If yes, then there are prefixes. Use the prefix to write the subscript for each element in the formula. Phosphorus pentachloride PCl5 Are the elements a metal & a non-metal? If yes, then you need to determine the charge on each element. Criss-cross the charges to find the formula. Sodium sulfate Na+1 and SO4 -2 Na2SO4

The Laws … The Law of Definite Proportions In samples of chemical compounds, the masses of the elements are always in the same proportions. The Law of Multiple Proportions Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.