1. Unit 3.3: Naming Compounds

2. Vocabulary: Monoatomic ion: an ion formed when a single element gains or loses electrons Polyatomic ion: tightly bound group of atoms that carry a charge and behave as a single unit Binary compound: a compound formed from two different elements; can be ionic or molecular. Acid: a compound that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water. Base: a compound that produces hydroxide (OH-) ions when dissolved in water. 2

3. I. Naming Ionic Compounds (9.1 -9.2) A.Binary compounds: “bi-” = 2; consist of two monoatomic ions that form an ionic bond. B.When naming ionic compounds, cation is listed first followed by anion, with “-ide” ending: 1.Ex: Na + + Cl -  NaCl; called sodium chloride 2.Ex: Ca 2+ + Cl -  CaCl 2 ; called calcium chloride C.Given the name of an ionic compound, determine ions and use “crossover” (criss-cross) rule to determine subscripts: 1.Barium iodide: barium = Ba 2+ ; iodide = I-, so… BaI 2 3

4. D.If a cation can have more than one possible charge, then denote the charge using Roman numerals in parentheses directly after the name of the ion: (the number tells the charge) 1.If Fe2+, then Fe(II) or Iron-2 ion a.Also called “ferrous” ion 2.If Fe3+, then Fe(III) or Iron-3 ion a.Also called “ferric” ion 3.If Cu+, then Cu(I) or Copper-1 ion a.Also called “cuprous” ion 4.If Cu2+, then Cu(II) or Copper-2 ion a.Also called “cupric” ion Less charge has “-ous” ending 4

5. E.Polyatomic ions: tightly bound group of atoms that carry a charge and behave as a single unit 1.Some ions are formed when nonmetals share valence electrons, but as a compound, carry a charge a.Ex: NH 4 + : nitrogen covalently bonded to 4 hydrogen atoms, but has one extra proton than electrons overall so +1 charge b.Ex: CO 3 2- : carbon covalently bonded to 3 oxygen atoms, but has two more electrons than protons overall so -2 charge 5

6. 2.End in “-ite” or “-ate” depending on the number of oxygen atoms that participate in the bond: a.Both ions have same charge, but a different number of oxygen atoms: 1)NO 2 - and NO 3 - b.If fewer oxygen atoms, then “-ite”, but if more oxygen atoms, then “-ate”: 1)Less O = “-ite”; more O = “-ate” a)Ex: NO 2 - = nitrite, but NO 3 - = nitrate 2)To help you remember: the one with more “ate” more oxygen Nitrite anion Nitrate anion 6

7. 3.If the polyatomic ion is bonded to a hydrogen ion (H+), then the name of the polyatomic ion begins with “hydrogen”: a.Ex: HCO 3 - = hydrogen carbonate b.Ex: HPO 4 2- = hydrogen phosphate 7

8. F.When writing formulas with polyatomic ions, treat the polyatomic ion as a single unit. 1.Ex: sodium nitrite: Na+ and NO 2 - ; so NaNO 2 2.If more than one polyatomic ion is needed to balance the charges of another ion, enclose the polyatomic ion in parentheses and use a subscript outside the parentheses to denote how many ions are needed. 3.Ex: write the formula for magnesium nitrate: a.Magnesium ion = Mg 2+ ; Nitrate ion = NO 3 - b.Crossover charges to get subscripts: Mg(NO 3 ) 2 8

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10. II. Naming Molecular Compounds (9.3) A.Molecular compounds: two nonmetals form covalent bonds by sharing valence electrons. B.But two elements can sometimes share electrons in more than one way: 1.Ex: CO and CO2 are both molecules made from carbon and oxygen. 10

11. C.Use prefixes to denote the number of each type of element participating in the bond: 1.All molecular compounds end in “-ide” 2.If only one of the first element in the compound, do not use “mono-” prefix for that first element. 3.The second element is named using number prefixes: 11 Also referred to as the Stock system

12. D.Writing molecular formulas from the name of a molecular compound is (somewhat) easier: 1.Write the name of the element followed by a subscript that is given as the prefix: a.Ex: carbon monoxide = one carbon, one oxygen, CO b.Ex: dinitrogen monoxide = two nitrogen, one oxygen, N 2 O c.Ex: dinitrogen tetroxide = two nitrogen, four oxygen, N 2 O 4 2.List least electronegative element first, most electronegative element second (with “-ide” ending). 12 Dinitrogen monoxide Dinitrogen tetroxide

13. III.Naming Acids (9.4) A.Acid: a compound that contains one or more hydrogen atoms and produces H + ions when dissolved in water. 1.General formula for an acid is H n X: a.where “X” is a mono- or polyatomic anion b.and “n” is the number of hydrogen ions that are combined with the anion to make it neutral. 13

14. B.Acids are named according to anion suffix: 1.if anion ends in “–ide”, then prefix is “hydro-” and ending is “-ic acid” a.ex: HCl – (chloride), so hydrochloric acid 2.if anion ends in “-ite”, then acid ends in “-ous acid” a.ex: H 2 SO 3 – (SO 3 2- = sulfite), then sulfurous acid 3.if anion ends in “-ate”, then acid ends in “-ic acid” a.ex: HNO 3 – (NO 3 - = nitrate), then nitric acid 14

15. C.Given an acid name, work backwards to determine formula: 1.If “hydro(anion)ic acid”, then H n X, X is a nonmetal a.Hydrobromic acid: based on bromine, so HBr b.Hydrosulfuric acid: based on sulfur, so H 2 S c.Your turn: hydrofluoric acid = ______ 2.If “-ic acid”, then H n X, X is a polyatomic “-ate” ion a.Sulfuric acid: based on sulfate (SO 4 2- ), so H 2 SO 4 b.Phosphoric acid: based on phosphate (PO 4 3- ), so H 3 PO 4 c.Your turn: carbonic acid = _______ 3.If “-ous acid”, then H n X, X is a polyatomic “-ite” ion a.Nitrous acid: based on nitrite (NO 2 - ), so HNO 2 b.Phosphorous acid: based on phosphite (PO 3 3- ), so H 3 PO 3 c.Your turn: hypochlorous acid = _______ 15

16. IV.Naming Bases (9.4) A.Base: a compound that produces hydroxide (OH - ) ions when dissolved in water. B.Named like other ionic compounds: 1.Cation first, followed by anion 2.Anion is most often hydroxide (-OH) C.Because –OH is a polyatomic ion, use parentheses when multiple hydroxide ions are needed to balance the cation: 1.Ex: Aluminum hydroxide – Al 3+, OH -  Al(OH) 3 16