Rules for Naming and Writing Compounds I. Ionic Bonds bonding between a metal and nonmetal 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 crisscross rule to balance for an electrically neutral compound. Name Symbol and Charge Formula 1. Sodium cloride Na + Cl NaCl 2. Magnesium oxide 3. Calcium bromide Mg 2+ O 2 MgO CaBr 2 4. Aluminum sulphide 5. Nickle (III) chloride (indicates charge) 6. Sodium thiosulphate (complex ion) Al 3+ S 2 Al 2 S 3 Ni 3+ Cl NiCl 3 Na 2 S 2 O 3
7. Aluminum silicate (complex ion) Al 2 (SiO 3 ) 3 (must bracket a complex ion with a subscript) 8. Ammonium phosphate NH 4 + PO 4 (NH 4 ) 3 PO 4 (bracket comples ion with a subscript) 9. Barium oxide Ba 2+ O 2 Ba 2 O 2 BaO (written with the lowest common multiple) 10. Lead(IV) oxide Pb 4+ O 2 Pb 2 O 4 PbO 2 (written again with the lowest numbers) II. Covalent Bonds sharing of bonds between two nonmetals 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 6 hexa 2 di 7 hepta 3 tri 8 octa 4 tetra 9 nona or ennea 5 penta 10 deca Name Symbols Formula 1. carbon monoxide C O CO 2. carbon dioxide C O CO 2 3. carbon tetrachloride C Cl CCl 4 4. dinitrogen monoxide N O N 2 O 5. dinitrogen pentafluoride N F N 2 F 5
III. Binary Acids contain hydrogen and a nonmetallic element are an aqueous solution of the pure compound have prefix hydro, suffix ic 1. hydroiodic acid HI(aq) 2. hydrobromic acid HBr(aq) 3. hydrochloric acid HCl(aq) 4. hydrofluoric acid HF(aq) 5. hydrocyanic acid 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 Acid name per ic acid ic acid ous acid hypo ous acid V. * Look up "ate" name number of oxygen decreases by one going down the chart acid name corresponds to name across chart add hydrogen, balance with crisscross rule. 1. Formula Ion Name Acid Name Formula ClO 4 ClO 3 ClO 2 perchlorate perchloric acid HClO 4(aq) chlorate* chloric acid HClO 3(aq) chlorite chlorous acid HClO 2(aq) ClO hypochlorite hypochlorous acid HClO (aq)
2. Formula Ion Name Acid Name Formula PO 5 PO 4 PO 3 perphosphate perphosphoric acid H 3 PO 5(aq) phosphate* phosphoric acid H 3 PO 4(aq) phosphite phosphorous H 3 PO 3(aq) PO 2 hypophosphite hypophosphorous acid H 3 PO 2(aq) Use crisscross 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 Formula 1. Copper(II) sulphate pentahydrate CuSO 4. 5H 2 O 2. Zinc chloride hexahydrate ZnCl 2. 6H 2 O 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 CO 3 2 Cations positively charged ions Rb + (aq) Rubidium ion Anions negatively charged ions P (aq) Phosphide ion name according to data booklet include the charge in the formula
KN0 3(s) K (aq) + + NO 3(aq) Potassium nitrate solid in a solution of H 2 O (l) breaks down into potassium ions and nitrate ions. EXERCISES I. II. III. 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 b. Name the following: 1. CaO 2. CdS 3. Ca 3 P 2 4. Mg 3 N 2 5. Mn 2 O 5 6. HgCl 2 7. Sn(N0 3 ) 4 8. K 2 Cr 2 0 7 a. Write the formulas for the following: 1. sulphur trioxide 2. phosphorous pentachloride 3. dinitrogen trioxide 4. dihydrogen monoxide b. Name the following: 1. SF 6 2. N 2 O 4 3. Cl 2 O 7 4. S 2 Cl 2 a. Write formulas for the following acids: 1. hydrofluoric acid 2. boric acid 3. hypochlorous acid 4. phosphorous acid b. Name the following acids 1. HI (aq) 2. HClO 4(aq)
IV. V. 3. H 2 SO 4(aq) 4. CH 3 COOH (aq) a. Write formulas for the following: 1. magnesium sulphate heptahydrate 2. calcium chloride dihydrate 3. sodium chloride octahydrate 4. aluminum chloride nonahydrate b. Name the following: 1. Na 2 CO. 3 10H 2 O 2. BaCl. 2 4H 2 O 3.. Na 2 SO 4 5H 2 O 4. Ba(OH) 2. 6H 2 O a. Write formulas for the following: 1. ammonium ion 2. bromate ion 3. acetate ion 4. phosphate ion b. Name the following ions: 1. K + (aq) 2. 3. Sr 2+ (aq) 2 CO 3 (aq) 4. NO 3 (aq)