Chemical Bonding
92 CHEMICAL BONDING [CHAP. 5
6.6 HYDRATES
Some stable ionic compounds are capable of bonding to a certain number of molecules of water per formula unit. Thus, copper(I1) sulfate forms the stable CuS0,-SH,O, with five molecules of water per CuSO, unit. This type of compound is called a hydrate. The name of the compound is the name of the anhydroirs (without water) compound with a designation for the number of water molecules appended. Thus, CuSO,.5H ,O is called copper(I1) sulfate pentahydrate. The 5, written on line, multiplies everything after it until the next centered dot or the end of the formula. Thus, included in CuS0,-SH,O there are ten H atoms and nine 0 atoms (five from the water and four in the sulfate ion 1.
Solved Problems
INTRODUCTION
6.1. Explain why the following three compounds, with such similar-looking formulas, have such different names:
AlCl CoCl3
PCI 3 Phosphorus trichloride A1 um in um chloride Cobalt( I I I) chloride
Ans. The three compounds belong to different nomenclature classes. Aluminum in its compounds always forms 3+ ions, and thus there is no need to state 3+ in the name. Cobalt forms 2+ and 3+
ions, and we need to designate which of these exists in this compound. PCI, is a binary nonmetal-nonmetal compound, using a prefix t o denote the number of chlorine atoms.
CHAP. 61 INORGANIC NOMENCLATURE
BINARY COMPOUNDS OF NONMETALS
107
6.2.
6.3.
6.4.
6.5.
6.6.
6.7.
6.8.
Name the following compounds: ( a ) CO, ( b ) SO,, (c) SO,, ( d ) CCl,, ( e ) PCl,, and (f) SF,.
A m ( a ) Carbon monoxide, (6) sulfur dioxide, (c) sulfur trioxide, ( d ) carbon tetrachloride, ( e ) phospho- rus pentachloride, and ( f ) sulfur hexafluoride.
Name the following compounds: ( a ) P,S, and ( b ) NC1,.
Ans. ( a ) Phosphorus pentasulfide and ( b ) nitrogen trichloride.
Name the following: ( a ) a compound with three oxygen atoms and one bromine atom per molecule; ( b ) a compound with one iodine atom and three chlorine atoms per molecule; and (c) a compound with one sulfur atom and four iodine atoms per molecule.
Ans. ( a ) Bromine trioxide, (6) iodine trichloride, and (c) sulfur tetraiodide.
Write formulas for each of the following compounds: ( a ) carbon tetrabromide, (6) sulfur dibromide, and (c) sulfur hexafluoride.
Ans. ( a ) CBr,, ( b ) SBr,, and (c) SF,.
Name ( a ) NH, and ( b ) H 2 0 . Ans. ( a ) Ammonia and ( b ) water.
Write formulas for each of the following compounds: ( a ) carbon tetrachloride, ( b ) carbon disulfide, and (c) carbon monoxide.
Ans. ( a ) CCI,, ( b ) CS,, and (c) CO.
Write formulas for each of the following compounds: ( a ) nitrogen monoxide, ( b ) nitrogen tribromide, and (c) nitrogen triiodide.
Ans. ( a ) NO, (6) NBr,, and ( c ) NI,.
NAMING IONIC COMPOUNDS 6.9. Name NH, and NH,+.
Ans. Ammonia and ammonium ion. Note carefully the difference between these names and formulas.
6.10. How can a beginning student recognize an ionic compound?
Ans. If the compound contains the NH,+ ion or a metal atom, it is most likely ionic. (It might have internal covalent bonds.) Otherwise, it is covalent, with no ions present.
6.11. In naming SO,’-, professional chemists might say “sulfate” or “sulfate ion,” but in naming Na’, they always say “sodium ion.” Explain the difference.
Ans. “Sulfate” is always an ion; “sodium” might refer to the element, the atom, or the ion, and so a distinction must be made.
6.12. Name the following ions: ( a ) Cu’, ( b ) Cr2+, (c) Pd2+, and ( d ) Hg,’+.
A m . ( a > Copper(1) ion, ( b ) chromium(I1) ion, (c) palladium(I1) ion, and ( d ) mercury(1) ion.
6.13. In which of the following periodic groups are located the metals that form ions of only one charge? ( a ) IA, ( b ) IIA, (c) IIIA, ( d ) VIA, (e) VIIA, (f) IB, ( g ) VIII, and ( h ) IIB.
Ans. ( a ) All the alkali metals (but not hydrogen). ( b ) All the alkaline earth metals. (c) Aluminum ion.
( f > Silver ion. ( h ) Zinc and cadmium ions.
108 INORGANIC NOMENCLATURE [CHAP. 6
6.14. Name the following compounds: ( a ) NaCIO, and (6) Ba(CIO),.
Ans. ( a ) Sodium chlorite and (6) barium hypochlorite. Note that parentheses enclose the CIO- ions, because there is a subscript to show that there are two of them. In (a), there is only one anion, which contains two oxygen atoms.
6.15. Explain one way to remember why mercury(1) ion has the Roman numeral I in it.
Ans. The average charge on the two Hg atoms in Hg,” is l + .
2 +
6.16. Explain why the formula for mercury(1) ion is Hg, Ans.
rather than Hg+.
The actual formula implies that the two mercury atoms are covalently bonded together.
6.17. Name the following ions: ( a ) Fe3+, ( b ) I-, (c) BrO,-, and ( d ) NO,-.
Ans. ( a ) Iron(II1) ion, (6) iodide ion, ( c ) bromite ion, and ( d ) nitrite ion.
6.18. Name the following ions: ( a ) PO,”, ( b ) S2-, and ( c ) SO,’-.
Ans. ( a ) Phosphite ion, ( b ) sulfide ion, and ( c ) sulfate ion.
6.19. Write formulas for each of the following compounds: ( a ) sodium bromide, (6) sodium bromate, (c) sodium bromite, ( d ) sodium hypobromite, and (e) sodium perbromate.
Am. ( a ) NaBr, ( b ) NaBrO,, ( c ) NaBrO,, ( d ) NaBrO, and (e) NaBrO,.
6.20. What is the difference between C10, and C103-?
Ans. The first is a compound, chlorine trioxide; the second is an ion, the chlorate ion. The chlorate ion has one extra electron, as shown by the minus sign.
6.21. ( a ) Write the formula for sodium sulfide, sodium sulfate, and sodium sulfite. (6) How many elements are implied in the compound by the -ide ending? by the -ite ending? by the -ate ending? ( c ) Name a particular element that is implied by the -ate ending.
Ans. ( a ) Na,S, Na2S0,, and Na,SO,.
( b ) -ide: at least two (a monatomic anion); -ate and -ite: at least three.
( c ) There is oxygen plus another element in the anion.
6.22. Name the following compounds: ( a ) FeF,, ( b ) FeF,, (c) FeO, ( d ) Fe,O,, and ( e ) FePO,.
Ans. ( a ) Iron(1I) fluoride, (6) iron(II1) fluoride, ( c ) iron(I1) oxide, ( d ) iron(II1) oxide, and ( e ) iron(II1) phosphate.
6.23. Name the following compounds: ( a ) NaCI, (6) Na,SO,, and ( c ) Na,PO,.
Ans. ( a ) Sodium chloride, ( 6 ) sodium sulfate, and ( c ) sodium phosphate. The only indication that there are one, two, and three sodium ions in the compounds is in the knowledge of the charges on the ions.
6.24. Name the following compounds: ( a ) NH,C1, (6) (NH,),S, and ( c ) (NH,)3P0,.
Ans. ( a ) Ammonium chloride, ( b ) ammonium sulfide, and ( c ) ammonium phosphate. Note that the last two formulas require parentheses around the ammonium ion, but that the first one does not since there is only one ammonium ion per formula unit.
CHAP. 61 INORGANIC NOMENCLATURE
Am mon i um Sodium Iron(II1) Cobalt(I1)
109
Chloride Sulfate Phosphate Hydroxide
NH,CI (NH,)2S04 (NH,),PO, NH,OH (unstable)
NaCl Na SO, Na ,PO, NaOH
FeCl
,
Fe 2(S04)3 FePO, Fe(OH),COCl 2
coso,
CoJPO, )2 C d O H ) 26.25.
6.26,
6.27.
6.28.
6.29.
6.30.
6.31.
6.32.
6.33.
Name the following compounds: ( a ) Ba,(PO,), and (6) Co2(S04),.
Ans. ( a ) Barium phosphate and ( b ) cobalt(II1) sulfate. We recognize that cobalt has a 3+ charge because two cobalt ions are needed to balance three sulfate ions, each of which has a 2- charge.
Fill in the table with the formula of the compound whose cation is named at the left and whose anion is named at the column head.
I
Chloride Sulfate Phosphate Hydroxide AmmoniumSodium Cobalt (I I) Iron(II1)
Ans.
Name the following ions: ( a ) BrO-, ( b ) NO,-, and ( c ) SO,2-.
Ans. ( a ) Hypobromite ion, ( 6 ) nitrate ion, and (c) sulfite ion.
Name the following ions: ( a ) C 2 H 3 0 2 - , ( b ) Cr2O,,-, ( c ) 022-, ( d ) M n 0 4 - , and ( e ) CrO,’-.
Ans. ( a ) Acetate ion, ( b ) dichromate ion, (c) peroxide ion, ( d ) permanganate ion, and ( e ) chromate ion.
Name the following ions: ( a ) H+, (6) OH-, ( c ) CN-, ( d ) NH,’, and ( e ) K+.
Ans. ( a ) Hydrogen ion, (6) hydroxide ion, (c) cyanide ion, ( d ) ammonium ion, and ( e ) potassium ion.
Write formulas for each of the following compounds: ( a ) sodium cyanide, ( b ) sodium hydrox- ide, and (c) sodium peroxide.
Ans. ( a ) NaCN, ( b ) NaOH, and (c) N a 2 0 2 (from Table 6-6).
What is the difference between the names phosphorus and phosphorous?
Ans. The first is the name of the element; the second is the name of the acid with fewer oxygen atoms than phosphoric acid-H,PO,, phosphorous acid.
Write formulas for each of the following compounds: ( a ) barium bromide, (6) copper(I1) bromate, and ( c ) cobalt(II1) fluoride.
Ans. ( a ) BaBr,, ( b ) Cu(BrO,),, and (c) CoF,.
Name and write formulas for each of the following: ( a ) the compound of sodium and bromine;
(6) the compound of magnesium and bromine; and ( c ) the compound of aluminum and bromine.
Am. ( a ) Sodium bromide, NaBr; (6) magnesium bromide, MgBr,; and (c) aluminum bromide, AIBr,.
The bromide ion has a 1- charge. The sodium, magnesium, and aluminum ions have charges of 1+, 2+, and 3+, respectively, and the subscripts given are the smallest possible to just balance the charges.
110 INORGANIC NOMENCLATURE [CHAP. 6
6.34.
6.35.
6.36.
6.37.
6.38.
6.39.
6.40.
Name and write formulas for each of the following: ( a ) the compound of sodium and sulfur;
( b ) the compound of magnesium and sulfur; and (c) the compound of aluminum and sulfur.
Ans. ( a ) Sodium sulfide, Na,S; ( h ) magnesium sulfide, MgS; and ( c ) aluminum sulfide, Al,S,. The sulfide ion has a 2- charge. The sodium, magnesium, and aluminum ions have charges of 1+, 2 + , and 3+, respectively, and the subscripts given are the smallest possible to just balance the charges.
Name and write formulas for each of the following: ( a ) two compounds of copper and bromine;
(6) two compounds of nickel and fluorine; and (c) two compounds of chromium and bromine.
(If necessary, see Table 6-4 for data.)
Ans. ( a ) Copper(1) bromide and copper(I1) bromide, CuBr and CuBr,; ( h ) nickel(I1) fluoride and nickel(1V) fluoride, NiF, and NiF,; and ( c ) chromium(l1) bromide and chromium(II1) bromide, CrBr, and CrBr,.
Name and write formulas for each of the following: ( a ) two compounds of iron and bromine;
( b ) two compounds of palladium and bromine; and (c) two compounds of mercury and bromine.
Ans. ( a ) Iron(1I) bromide and iron(II1) bromide, FeBr, and FeBr,; ( h ) palladium(I1) bromide and palladium(1V) bromide, PdBr, and PdBr,; and (c mercury(1) bromide and mercury(I1) bromide, Hg,Brz and HgBr,. (The charges on the cations can be obtained from Table 6-4.)
Name and write formulas for each of the following: ( a ) the compound of bromine and sodium, ( b ) the compound of bromine and magnesium, and ( c ) the compound of bromine and aluminum.
Ans. This answer is exactly the same as that of Problem 6.33. The metal is named first even if it is given last in the statement o f the problem.
What are the charges on the following ions? ( a ) cyanide, ( b ) barium ion, ( c ) sulfide, ( d ) nitride, and (e) chloride.
AnS. ( a ) 1-, ( b ) 2+, ( c ) 2-, ( d ) 3-, and ( e ) 1-.
Using the periodic table if necessary, write formulas for the following compounds: ( a ) hydrogen bromide, ( b ) magnesium chloride, (c) barium sulfide, ( d ) aluminum fluoride, ( e ) beryllium bromide, (f) barium selenide, and ( 8 ) sodium iodide.
Ans. ( a ) HBr, ( h ) MgCl,, ( c ) BaS, ( d ) AIF,, ( e ) BeBr,, ( f ) Base, and ( g ) Nal.
Write the formula for each of the following compounds: ( a ) hydrogen iodide, ( b ) calcium chloride, (c) lithium oxide, ( d ) silver nitrate, (e) iron(I1) sulfide, (f) aluminum chloride, ( g ) ammonium sulfate, ( h ) zinc carbonate, ( i ) iron(II1) oxide, ( j ) sodium phosphate, ( k ) iron(I1) acetate, ( f ) ammonium cyanide, and ( r n ) copper(I1) chloride.
Ans. ( a ) HI, ( b ) CaCI,, ( c ) Li,O, ( d ) AgNO,, ( e ) FeS, ( f ) AICI,, ( g ) (NH,)?SO,, ( h ) ZnCO,, ( i ) Fe,O,, C j ) Na,PO,, ( k ) Fe(C,H,O,),, ( I ) NH,CN, and ( r n ) CuCl,.
NAMING INORGANIC ACIDS
6.41. Name the following acids: ( a ) HCl, ( b ) HCIO, (c) HCIO,, ( d ) HCIO,, and ( e ) HCIO,.
Ans. ( a ) Hydrochloric acid, ( h ) hypochlorous acid, (c) chlorous acid, ( d ) chloric acid, and ( e ) perchloric acid.
CHAP. 61 INORGANIC NOMENCLATURE 111