Rules for Naming

Rules for Naming and Writing Compounds
I. Ionic Bonds • bonding between a metal and non-metal or the bond between a positive ion and a negative ion forming a binary compound. • end in the suffix "ide" • Or bonding between a metal and a complex ion. Steps in writing formulas:
• • • •

Use a periodic table of elements and of ions. Write the symbol and charge of the cation first (positive ion) Write the symbol and charge of the anion next (negative ion) Use criss-cross rule to balance for an electrically neutral compound. Name Symbol and Charge Na+ Mg2+ ClO2Formula NaCl MgO

1. 2.

Sodium cloride Magnesium oxide Calcium bromide Aluminum sulphide Nickle (III) chloride
(indicates charge)

3.

CaBr2

4.

Al3+ Ni3+

S2Cl-

Al2S3

5.

NiCl3

6.

Sodium thiosulphate
(complex ion)

Na2S2O3

7.

Aluminum silicate
(complex ion)

Al2(SiO3)3
(must bracket a complex ion with a subscript)

8.

Ammonium phosphate

NH4+

PO43-

(NH4)3PO4
(bracket comples ion with a subscript)

9.

Barium oxide

Ba2+

O2-

Ba2O2

BaO
(written with the lowest common multiple)

10.

Lead(IV) oxide

Pb4+

O2-

Pb2O4

PbO2
(written again with the lowest numbers)

II.

Covalent Bonds • sharing of bonds between two non-metals • end in "ide" Steps in writing formulas:
• • •

refer to periodic table of elements write symbol of each element use prefix system for naming. 1 - mono 2 - di 3 - tri 4 - tetra 5 - penta Name 6 - hexa 7 - hepta 8 - octa 9 - nona or ennea 10 - deca Symbols C O C O C Cl Formula CO CO2 CCl4 N2O N2F5

1. 2. 3. 4. 5.

carbon monoxide carbon dioxide carbon tetrachloride dinitrogen monoxide dinitrogen pentafluoride

N O N F

III.

Binary Acids • contain hydrogen and a nonmetallic element • are an aqueous solution of the pure compound • have prefix hydro, suffix ic 1. 2. 3. 4. 5. hydroiodic acid hydrobromic acid hydrochloric acid hydrofluoric acid hydrocyanic acid HI(aq) HBr(aq) HCl(aq) HF(aq) HCN(aq)
(exception to the rule since it is not a binary compound)

IV.

Oxyacids • contain hydrogen, oxygen and a third element • name as though ionic then convert to the acid name. Ionic name per __________ ate _________ ate* __________ ite hypo __________ ite V. * Look up "ate" name
• • •

Acid name per _______ ic acid _______ ic acid _______ ous acid hypo _______ ous acid

number of oxygen decreases by one going down the chart acid name corresponds to name across chart add hydrogen, balance with criss-cross rule. Formula ClO4ClO3ClO2ClOIon Name perchlorate chlorate* chlorite hypochlorite Acid Name perchloric acid chloric acid chlorous acid hypochlorous acid Formula HClO4(aq) HClO3(aq) HClO2(aq) HClO(aq)

1.

2.

Formula PO53PO43PO33PO23-

Ion Name perphosphate phosphate* phosphite hypophosphite

Acid Name perphosphoric acid phosphoric acid phosphorous hypophosphorous acid

Formula H3PO5(aq) H3PO4(aq) H3PO3(aq) H3PO2(aq)
Use criss-cross rule

VII.

Hydrated Compounds • ionic compounds that produce water when decomposed by heating • name as ionic compound • indicate number of water molecules using previous prefixes of "di", "tri", etc. and the ending hydrate. Name 1. 2. Copper(II) sulphate pentahydrate Zinc chloride hexahydrate Formula CuSO4 . 5H2O ZnCl2 . 6H2O

VIII.

Ions
•

an atom that has lost or gained one or more electrons. Ions usually occur in an aqueous solution.

Complex Ions
•

groups of atoms which share electrons and exist together in aqueous solution, i.e., carbonate ion CO32-

Cations
•

positively charged ions Rb+(aq)

Rubidium ion

Anions
• • •

negatively charged ions P3-(aq) name according to data booklet include the charge in the formula

Phosphide ion

KN03(s)

K(aq)+ + NO-3(aq)

Potassium nitrate solid in a solution of H2O(l) breaks down into potassium ions and nitrate ions.

EXERCISES
I. a. Write the formulas for the following: 1. silver chloride 2. calcium fluoride 3. aluminum oxide 4. iron(III) sulphide 5. lead(IV) oxide 6. sodium dichromate 7. calcium chlorite 8. ammonium phosphate Name the following: 1. CaO 2. CdS 3. Ca3P2 4. Mg3N2 5. Mn2O5 6. HgCl2 7. Sn(N03)4 8. K2Cr207 Write the formulas for the following: 1. sulphur trioxide 2. phosphorous pentachloride 3. dinitrogen trioxide 4. dihydrogen monoxide Name the following: 1. SF6 2. N2O4 3. Cl2O7 4. S2Cl2 Write formulas for the following acids: 1. hydrofluoric acid 2. boric acid 3. hypochlorous acid 4. phosphorous acid Name the following acids 1. HI(aq) 2. HClO4(aq)

b.

II. a.

b.

III. a.

b.

3. 4. IV. a.

H2SO4(aq) CH3COOH(aq)

b.

Write formulas for the following: 1. magnesium sulphate heptahydrate 2. calcium chloride dihydrate 3. sodium chloride octahydrate 4. aluminum chloride nonahydrate Name the following: 1. Na2CO3 . 10H2O 2. BaCl2 . 4H2O 3. Na2SO4 . 5H2O 4. Ba(OH)2 . 6H2O Write formulas for the following: 1. ammonium ion 2. bromate ion 3. acetate ion 4. phosphate ion Name the following ions: 1. K+(aq) 2. Sr2+(aq) 3. CO32-(aq) 4. NO3-(aq)

V. a.

b.