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Home , Barium chloride, Binary acid, Cadmium iodide, Caesium sulfide, Potassium oxide

Common Monoatomic

Cations Anions Charge Formula Name Charge Formula Name

H+ H- hydride Li + lithiumF- fluoride +1 Na + -1 Cl - K+ Br - Cs + I- Ag +

Mg 2+ O2- Ca 2+ S2- +2 Sr 2+ -2 Ba 2+ Zn 2+ Cd 2+ 3+ +3 Al -3 N3- nitride

• Ionic Compounds – often a metal + – anion (nonmetal), add “ide ” to element name

BaCl 2 barium chloride

K2O potassium oxide

Mg(OH) 2 magnesium

KNO 3 potassium nitr ate

oxoanions often end with ate

1 Some Common Polyatomic Ions Formula NameFormula Name Cations + + ammonium H3O hydronium NH 4 Common Anions

- acetate 2- CH 3COO CO 3 carbonate - cyanide 2- CN CrO 4 chromate OH - hydroxide 2- Cr 2O7 dichromate

- chlorate 2- ClO 3 O2 - nitrite SO 2- sulfite NO 2 3 - 2- NO 3 nitrate SO 4

3- - permanganate PO 4 phosphate MnO 4

Oxoanions - NO 2 “ite” nitrite

e.g. forms 2 oxoanions

- NO 3 “ate” nitrate

• Some elements can form more than 2 oxoanions e.g. ClO - hypochlorite (“ hypo” – least)

- ClO 2 chlorite - order as before ClO 3 chlorate - ClO 4 perchlorate (“per” – most)

• Anions with hydrogen (add one positive charge i.e addition of H +) e.g. S 2- + H + HS -

2- + - CO 3 + H HCO 3 hydrogen carbonate OH - hydroxide

2 Acids

If formula begins with H and the compound is in aqueous solution, it’s normally a binary acid. Add “ hydro………ic acid” to root of the element.

e.g. HCl HCl(aq)

OXOACIDS (parents of oxoanions)

H+ - NO 2 nitrite ion HNO 2 nitrous acid H+ - NO 3 nitrate ion HNO 3 nitric acid

Generally “ous” in the parent acid comes from “ite” in the oxoanion and “ic” in the parent acid comes from “ate” in the oxoanion

2H + 2- SO 3 sulfite ion H2SO 3 sulfurous acid + 2- 2H SO 4 sulfate ion H2SO 4 sulfuric acid

• Transition metal ionic compounds – indicate charge on metal with Roman numerals

- FeCl 2 2 Cl -2 so Fe is +2 (II) chloride (ferrous chloride)

- FeCl 3 3 Cl -3 so Fe is +3 iron(III) chloride (ferric chloride)

2- Cr 2S3 3 S -6 so Cr is +3 (III) sulfide

3 Hydrates (compounds that contain water molecules): add “hydrate” preceded by prefix indicating the number of water molecules

2+ 2- e.g. CuSO 4 Cu , SO 4 (II) sulfate . CuSO 4 5H 2O (5 water molecules, called water of hydration)

copper(II) sulfate pentahydrate

Numerical Prefixes for Hydrates and Binary Covalent Compounds

1 mono- 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- 9 nona- 10 deca-

………… often molecular

4 s Molecular compounds ne eli id Gu – or nonmetals +

– common names H 2O, NH 3, CH 4

– element further left in periodic table is 1 st – element closest to bottom of group is 1 st – if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom – last element ends in ide

Examples:

HI SO 2 dioxide NF nitrogen trifluoride 3 N2Cl 4 dinitrogen tetrachloride

Sample Problem Naming Binary Ionic Compounds

PROBLEM: Name the formed from the following pairs of elements: (a) magnesium and nitrogen (b) and cadmium

(c) strontium and fluorine (d) sulfur and caesium

PLAN: Use the periodic table to decide which element is the metal and which the nonmetal. The metal (cation) is named first and we use the -ide suffix on the nonmetal name root.

SOLUTION: (a) magnesium nitride

(b) cadmium iodide

(c) strontium fluoride

(d) caesium sulfide

5 Sample Problem Determining Formulas of Binary Ionic Compounds

PROBLEM: Write empirical formula for the compounds named in the previous Sample Problem.

PLAN: Compounds are neutral. We find the smallest number of each ion which will produce a neutral formula. Use subscripts to the right of the element symbol.

SOLUTION:

2+ 3- 2+ 3- (a) magnesium nitride (a) Mg and N ; three Mg (6+) and two N (6-); Mg 3N2

2+ - 2+ - (b) cadmium iodide (b) Cd and I ; one Cd and two I (2-); CdI 2

(c) strontium fluoride 2+ - 2+ - (c) Sr and F ; one Sr and two F (2-); SrF 2

+ 2- + 2- (d) caesium sulfide (d) Cs and S ; two Cs (2+) and one S ; Cs 2S

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