47374_05_p33-42.qxd 2/9/07 7:52 AM Page 33
5
Names and Formulas of Compounds
5.1
a. When a sodium atom loses its valence electron, its second energy level has a complete octet.
b. Group 1A (1) and 2A (2) elements can lose 1 or 2 electrons to attain a noble gas arrangement.
Group 8A (18) elements already have an octet of valence electrons, so they do not lose or gain
electrons and are not normally found in compounds.
5.2
a. When a chlorine atom gains a valence electron, its third energy level has a complete octet.
b. Group 7A (17) elements can gain 1 electron to attain a noble gas arrangement. Group 8A (18)
elements already have an octet of valence electrons, so they do not lose or gain electrons and
are not normally found in compounds.
5.3
Atoms with 1, 2, or 3 valence electrons lose those electrons to form ions.
a. 1
b. 2
c. 3
d. 1
e. 2
5.4
Atoms with 5, 6, or 7 valence electrons gain electrons when they form ions.
a. 1
b. 2
c. 3
d. 1
e. 3
5.5
Atoms form ions by losing or gaining electrons to achieve the same electron arrangement of their
nearest noble gas.
a. Na! has an electron arrangement 2, 8, which is the same as neon (Ne).
b. Mg2! has an electron arrangement 2, 8, which is the same as neon (Ne).
c. K! has an electron arrangement 2, 8, 8, which is the same as argon (Ar).
d. O2" has an electron arrangement 2, 8, which is the same as neon (Ne).
e. F" has an electron arrangement 2, 8, which is the same as neon (Ne).
5.6
a. He
5.7
Atoms form ions by losing or gaining electrons to achieve the same electron arrangement of their
nearest noble gas. Elements in Groups 1A (1), 2A (2), and 3A (13) lose valence electrons,
whereas elements in Groups 5A (15), 6A (16), and 7A (17) gain valence electrons to complete
octets.
b. Kr
c. Ar
d. Ne
e. Kr
a. Mg loses 2 e"
d. Na loses 1 e"
b. P gains 3 e"
e. Al loses 3 e"
c. Group 7A (17) gains 1 e"
5.8
a. gain 2 e"
d. lose 1 e"
b. lose 2 e"
e. gain 3 e"
c. gain 1 e"
5.9
a. Li! (3!, 2" # 1!)
d. Fe3! (26!, 23" # 3!)
b. F" (9!, 10" # 1")
e. Zn2! (30!, 28" # 2!)
c. Mg2! (12!, 10" # 2!)
5.10 a. 8 protons, 10 electrons
c. 35 protons, 36 electrons
e. 38 protons, 36 electrons
b. 19 protons, 18 electrons
d. 16 protons, 18 electrons
5.11 A metal and a nonmetal are most likely to form an ionic compound.
a. (Li and Cl) and c. (K and O) would form ionic compounds.
5.12 b. (Mg and Cl) and d. (K and S) will form ionic compounds.
33
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Chapter 5
5.13 a. Potassium loses 1 e", and chlorine gains 1 e"
K +
–
→ K+ +
Cl
→ KCl
Cl
b. Calcium loses 2 e", and two chlorine atoms each gain 1 e".
→ Ca2+ + 2
Ca + Cl + Cl
–
→ CaCl2
Cl
c. Each of three sodium atoms lose 1 e", and the nitrogen gains 3 e".
→ 3Na+ +
Na + Na + Na + N
5.14 a.
b.
Mg +
Al +
S
Cl +
c. Li + Li +
5.15 a.
b.
c.
d.
e.
Na2O
AlBr3
BaO
MgCl2
Al2S3
5.16 a. AlCl3
5.17 a.
b.
c.
d.
Cl +
Cl
S
b. BaBr2
Cl
–
+
Cl
–
+
Cl
2–
O
# 2(!) ! 1(2") # 0
# 1(3!) ! 3(") # 0
# 1(2!) ! 1(2") # 0
# 1(2!) ! 2(1") # 0
# 2(3!) ! 3(2") # 0
c. Li2S
Na2S
K3N
AlI3
Li2O
–
→ Al3+ +
Check: 2Na! and O2"
Check: 1Al3! and 3Br"
Check: Ba2! and O2"
Check: Mg2! and 2Cl"
Check: 2Al3!and 3S2"
b. CaS
→ Na3N
2–
O → Li+ + Li+ +
Ions: Na ! and S2" :
Ions: K! and N3" :
Ions: A13! and I" :
Ions: Li! and O2" :
5.18 a. CaCl2
5.19 a.
b.
c.
d.
→ Mg2+ +
3–
N
d. K3N
e. KI
Check: 2Na! and S2"
Check: 3K! and N3"
Check: Al3! and I"
Check: 2Li! and O2"
c. Na3P
# 2(!) ! 1(2") # 0
# 3(!) ! 1(3") # 0
# 1(3!) ! 3(1") # 0
# 2(!) ! 1(2") # 0
d. MgO
Chlorine in Group 7A (17) gains 1 electron to form chloride ion Cl".
Potassium in Group 1A (1) loses 1 electron to form potassium ion K!.
Oxygen in Group 6A (16) gains 2 electrons to form oxide ion O2".
Aluminum in Group 1A (1) loses 3 electrons to form aluminum ion Al3!.
5.20 a. F"
b. Ca2!
c. Na!
d. Li!
5.21 a. potassium ion
b. sulfide ion
c. calcium ion
d. nitride ion
5.22 a. magnesium
b. barium
c. iodide
d. chloride
5.23 In the name for an ionic compound, the metal ion is named first followed by the nonmetal ion
name ending in ide.
a. Ions: Al3! aluminum and O2" oxide : aluminum oxide
b. Ions: Ca2! calcium and chloride Cl" : calcium chloride
c. Ions: Na! sodium and O2" oxide
: sodium oxide
34
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Names and Formulas of Compounds
d. Ions: Mg2! magnesium and nitride N3" : magnesium nitride
: potassium iodide
e. Ions: K! potassium and I" iodide
f. Ions: Ba2! barium and fluoride F"
: barium fluoride
5.24 a. magnesium chloride
d. lithium bromide
b. potassium phosphide
e. magnesium oxide
c. lithium sulfide
f. strontium bromide
5.25 A Roman numeral is used to specify the positive charge on the transition metal in the compound,
when that transition metal can have more than one cation.
5.26 Because calcium ion only has a !2 charge, the name calcium is sufficient. However, copper ions
can have either a !1 or a !2 charge, which requires a Roman numeral to indicate which copper
ion is present.
5.27 a. iron(II)
d. lead(IV)
b. copper(II)
e. chromium(III)
c. zinc
f. manganese(II)
5.28 a. silver
d. tin(II)
b. copper(I)
e. gold(III)
c. iron(III)
f. nickel(II)
5.29 For metal ions with variable charge, determine the ionic charge and use it as a Roman numeral
following the name of the metal.
a. Sn2! and 2Cl" : tin(II) chloride
b. Fe2! and O2" : iron(II) oxide
c. Cu! and S2" : copper(I) sulfide
d. Cu2! and S2" : copper(II) sulfide
e. Cd2! and Br" : cadmium bromide
f. Hg2! and Cl" : mercury(II) chloride
5.30 a. silver phosphide
d. gold(III) chloride
5.31 a.
b.
c.
d.
? ! 3("1) # 0
2? ! 3("2) # 0
? ! 4("1) # 0
? ! 2("1) # 0
5.32 a. !2
5.33 a.
b.
c.
d.
e.
b. lead(II) sulfide
e. chromium(III) oxide
? # 3!
2? # 6 ! ? # 3!
? # 4!
? # 2!
b. !2
c. !3
:
:
:
:
c. tin(IV) oxide
f. cobalt(II) sulfide
Au3!
Fe3!
Pb4!
Sn2!
d. !3
Ions: Mg2! and Cl" : MgCl2
Ions: Na! and S2" : Na2S
Ions: Cu! and O2" : Cu2O
Ions: Zn2! and P3" : Zn3P2
Ions: Au3! and N3" : AuN
5.34 a. Fe2O3
b. BaF2
3!
c. SnCl4
5.35 a.
b.
c.
d.
e.
f.
Ions: Co and Cl
Ions: Pb4! and O2"
Ions: Ag! and Cl"
Ions: Ca2! and N3"
Ions: Cu! and P3"
Ions: Cr2! and Cl"
5.36 a.
b.
c.
d.
e.
f.
Ions: Sn4! and O2" : SnO2
Ions: Fe3! and S2" : Fe2S3
Ions: Mn4! and O2" : MnO2
Ions: Cr3! and I"
: CrI3
Ions: Li! and N3" : Li3N
Ions: Au! and O2" : Au2O
"
d. Ag2S
e. CuCl2
: CoCl3
: PbO2
: AgCl
: Ca3N2
: Cu3P
: CrCl2
35
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Chapter 5
5.37 The most common forms of negatively charged polyatomic ions end in ate; one O less end in ite.
A hydrogen in front is named as hydrogen or bi.
a. bicarbonate HCO3"
b. ammonium NH4!
c. phosphate PO43"
"
"
d. hydrogen sulfate HSO4
e. hypochlorite ClO
5.38 a. NO2"
b. SO32"
c. OH"
d. PO33"
e. C2H3O2"
5.39 a. sulfate
b. carbonate
c. phosphate
d. nitrate
e. perchlorate
5.40 a. hydroxide
e. chromate
b. hydrogen sulfite (or bisulfite)
c. cyanide
d. nitrite
5.41
NO2"
CO32"
HSO4"
PO43"
lithium
nitrite
LiNO2
copper(II)
nitrite
Cu(NO2)2
barium
nitrite
Ba(NO2)2
lithium
carbonate
Li2CO3
copper(II)
carbonate
CuCO3
barium
carbonate
BaCO3
lithium
hydrogen sulfate
LiHSO4
copper (II)
hydrogen sulfate
Cu(HSO4)2
barium hydrogen
sulfate
Ba(HSO4)2
lithium
phosphate
Li3PO4
copper (II)
phosphate
Cu3(PO4)2
barium
phosphate
Ba3(PO4)2
NO3"
HCO3"
SO32"
HPO42"
NH4!
ammonium
nitrate
NH4NO3
ammonium
hydrogen
carbonate
NH4HCO3
ammonium sulfite
(NH4)2SO3
ammonium
hydrogen
phosphite
(NH4)2HPO4
Al3!
aluminum
nitrate
Al(NO3)3
aluminum
hydrogen
carbonate
Al(HCO3)3
aluminum sulfite
Al2(SO3)3
aluminum
hydrogen
phosphite
Al2(HPO4)3
Pb4!
lead(IV)
nitrate
Pb(NO3)4
lead(IV)
hydrogen
carbonate
Pb(HCO3)4
lead(IV) sulfite
Pb(SO3)2
lead(IV)
hydrogen
phosphite
Pb(HPO4)2
Li !
Cu2!
Ba2!
5.42
5.43 a.
b.
c.
d.
e.
f.
36
The polyatomic ion is CO32"; the compound is sodium carbonate.
The polyatomic ion is NH4!; the compound is ammonium chloride.
The polyatomic ion is PO43"; the compound is lithium phosphate.
The polyatomic ion is NO2"; the compound is copper(II) nitrite.
The polyatomic ion is SO32"; the compound is iron(II) sulfite.
The polyatomic ion is C2H3O2"; the compound is potassium acetate.
47374_05_p33-42.qxd 2/9/07 7:52 AM Page 37
Names and Formulas of Compounds
5.44 a.
c.
d.
e.
OH"; potassium hydroxide
b. NO3"; sodium nitrate
CO32"; copper(II) carbonate
HCO3"; sodium hydrogen carbonate (or sodium bicarbonate)
f. ClO"; calcium hypochlorite
SO42"; barium sulfate
5.45 Write the positive and negative ions. Then use charge balance to write the formula.
a. Ions: Ba2! and 2OH" : Ba(OH)2
b. Ions: 2Na! and SO42" : Na2SO4
c. Ions: Fe2! and 2NO3" : Fe(NO3)2
d. Ions: 3Zn2! and 2PO43" : Zn3(PO4)2
e. Ions: 2Fe3! and 3CO32" : Fe2(CO3)3
5.46 a. Al(ClO3)3
b. (NH4)2O
c. Mg(HCO3)2
d. NaNO2
e. Cu2SO4
5.47 a. This is an ionic compound with Al3! ion and the sulfate SO42" polyatomic ion. The correct
name is aluminum sulfate.
b. This is an ionic compound with Ca2! ion and the carbonate CO32" polyatomic ion. The correct
name is calcium carbonate.
c. This is an ionic compound with Cr3! and O2". Because chromium has variable valences, a
Roman numeral is used to indicate the 3 ! charge. The correct name is chromium(III) oxide.
d. This is an ionic compound with sodium ion Na! and the PO43" polyatomic ion. The correct
name is sodium phosphate.
e. This ionic compound contains two polyatomic ions, ammonium NH4! and sulfate SO42". It is
named ammonium sulfate.
f. This is an ionic compound containing the variable metal ion Fe3! and oxide ion O2". It is
named using the Roman numeral as iron(III) oxide.
5.48 a. cobalt(III) phosphate
c. iron(II) sulfate
e. copper(I) oxide
b. magnesium phosphate
d. magnesium sulfate
f. tin(II) fluoride
5.49 The nonmetallic elements that are not noble gases are likely to form covalent bonds.
5.50 A bond forms between Na and Cl when an electron is lost by Na and gained by Cl.
The bond that forms is an ionic bond. A bond forms between N and Cl when a pair of electrons,
one from each atom, is shared between the two atoms. The bond that formed is a covalent bond.
5.51 a. When two H atoms share, each has 2 valence electrons. In H2, there is 1 bonding pair and no
lone pair.
b. The Br atom achieves an octet by sharing a valence electron with one H atom to give 8 valence
electrons, 1 bonding pair, and 3 lone pairs on the Br atom.
c. Each Br atom achieves an octet by sharing 1 valence electron to give a total of 14 valence
electrons, 1 bonding pair between the Br atoms, and 6 lone pairs (3 lone pairs for each Br atom).
5.52 a. 8 valence electrons, 2 bonding pairs, and 2 lone pairs
b. 8 valence electrons, 3 bonding pairs, and 1 lone pair
c. 20 valence electrons, 2 bonding pairs, and 8 lone pairs
5.53 When naming covalent compounds, prefixes are used to indicate the number of each atom as
shown in the subscripts of the formula. The first nonmetal is named the same as the element; the
second nonmetal changes the ending of the element name to ide.
a. one phosphorus atom and three (tri) bromine atoms; phosphorus tribromide
b. one carbon atom and four (tetra) bromine atoms; carbon tetrabromide
c. one silicon atom and two oxygen atoms; silicon dioxide
d. one hydrogen atom and one fluorine atom; hydrogen fluoride
e. one nitrogen atom and three (tri) iodine atoms; nitrogen triiodide
37
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Chapter 5
5.54 a. carbon disulfide
d. phosphorus trichloride
b. diphosphorus pentoxide
e. dinitrogen tetroxide
c. dichlorine oxide
5.55 When naming covalent compounds, prefixes are used to indicate the number of each atom as
shown in the subscripts of the formula. The first nonmetal is named the same as the element; the
second nonmetal changes the ending of the element name to ide.
a. two (di) nitrogen atoms and three (tri) oxygen atoms; dinitrogen trioxide
b. one nitrogen atom and three (tri) chlorine atoms; nitrogen trichloride
c. one silicon atom and four (tetra) bromine atoms; silicon tetrabromide
d. one phosphorus atom and five (penta) chlorine atoms; phosphorus pentachloride
e. one sulfur atom and three (tri) oxygen atoms; sulfur trioxide
5.56 a. silicon tetrafluoride
d. sulfur dioxide
b. iodine tribromide
e. dinitrogen oxide
c. carbon dioxide
5.57 The prefixes in the names of covalent compounds indicate the number of each type of atom, which
is placed as a subscript in the formula. When there is no prefix there is one atom in the formula.
a. carbon (1C) and tetrachloride (4Cl) # CCl4
b. carbon (1C) and monoxide (1O)
# CO
c. phosphorus (1P) and trichloride (3Cl) # PCl3
d. dinitrogen (2N) and tetroxide (4O)
# N2O4
5.58 a. SO2
b. SiCl4
c. IF5
d. N2O
5.59 The prefixes in the names of covalent compounds indicate the number of each type of atom, which
is placed as a subscript in the formula. When there is no prefix, there is one atom in the formula.
a. oxygen (1O) and difluoride (2F) # OF2
b. boron (1B) and trifluoride (3F) # BF3
c. dinitrogen (2N) and trioxide (3O) # N2O3
d. sulfur (1S) and hexafluoride (6F) # SF6
5.60 a. SBr2
b. CS2
c. P4O6
d. N2O5
5.61 a. aluminum chloride
d. tin(II) nitrate
b. sulfur trioxide
e. copper(II) chlorite
c. dinitrogen oxide
5.62 a. nitrogen
d. nickel (II) sulfate
b. magnesium hypobromite
e. iron (III) sulfide
c. silicon tetrafluoride
5.63 a.
b.
c.
d.
15 protons make it phosphorus; 18 electrons gives a charge of 3"; P3".
8 protons and 8 electrons make it a neutral oxygen (O) atom.
30 protons make it zinc; 28 electrons gives a charge of 2!; Zn2!.
26 protons make it iron; 23 electrons gives a charge of 3!; Fe3!.
5.64 a. X is in Group 1A (1); Y is in Group 6A (16)
c. X!, Y2"
d. X2Y
e. XCl
5.65 1. H (E)
2. Li (C)
3. Li!(A)
b. ionic
f. YCl2
4. H! (B)
5.66 calcium ions, Ca2!; hydroxide ions, OH"; and phosphate ions, PO43"
38
5. N3" (D)
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Names and Formulas of Compounds
5.67
Period
Electron-dot
Symbols
Formula of
Compound
Name of Compound
2
X and
Y
Li3N
lithium nitride
4
X and
Y
CaBr2
calcium bromide
3
X and
Y
Al2S3
aluminum sulfide
Formula of
Compound
Name of Compound
Be3N2
beryllium nitride
Al2S3
aluminum sulfide
SrI2
strontium iodide
5.68
Electron-dot
Symbols
Period
X and
2
X and
3
X and
5
Y
Y
Y
5.69
Electron Arrangements
Electron-dot
Symbols
Cations
Anions
Formula of
Compound
Name of Compound
2, 8, 2
Mg
N
Mg2!
N3"
Mg3N2
magnesium nitride
K
O
K!
O2"
K2O
potassium oxide
Br
Al3!
Br "
AlBr3
aluminum bromide
2, 5
2, 8, 8, 1 2, 6
2, 8, 3
2, 8, 18, 7
Al
5.70
Formula of
Compound
Name of
Compound
S
Li2S
lithium sulfide
Ca
P
Ca3P2
calcium phosphide
Na
Cl
NaCl
sodium chloride
Electron Arrangements
Electron-dot Symbols
2, 1
2, 8, 6
Li
2, 8, 8, 2 2, 8, 5
2, 8, 1
2, 8, 7
39
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Chapter 5
5.71 a. Ne
d. Ne
b. Ne
e. He
c. Ar
5.72 a. Ne
d. Ne
b. Kr
e. Ar
c. Ar
5.73 a.
b.
c.
d.
An element that forms an ion with a 2! charge would be in Group 2A (2).
The electron-dot symbol for an element in Group 2A (2) is • X •.
Be is the Group 2A (2) element in Period 2.
Three ions, each with a 2! charge, are needed to balance two N3", which gives a formula X3N2.
5.74 a.
b.
c.
d.
X is in Group 1A (1); Y is in Group 6A (16).
X!, Y2"
X2Y
XCl
5.75 a.
b.
c.
d.
Tin(IV) is Sn4!.
The Sn4! ion has 50 protons and 46 electrons.
The Sn4! ion is balanced with two O2" ions; SnO2.
Three Sn4! ions are needed to balance four PO43" ions; Sn3(PO4)4.
5.76 a.
b.
c.
d.
Gold (III) is Au3!.
The Au3! ion has 79 protons and 76 electrons.
Two Au3! ions are balanced with three SO42" ions; Au2(SO4)3.
One Au3! ion balance three Cl" ions; AuCl3.
5.77 a. X as a X3! ion would be in Group 3A (13).
b. X as a X2" ion would be in Group 6A (16).
c. X as a X4! ion would be in Group 4A (14).
5.78 a. 3A (13)
b. 6A (16)
3!
c. 4A (14)
5.79 a.
c.
e.
g.
Fe is the iron(III) ion; iron(III) chloride.
aluminum carbonate
magnesium carbonate
Cu2! is the copper(II) ion: copper(II) sulfide.
5.80 a.
c.
e.
g.
tin(II) sulfate
manganese(II) sulfide
chromium(III) phosphite
calcium chloride
5.81 a.
b.
c.
d.
e.
Copper(I) is Cu! and nitride is N3"; Cu3N.
Potassium ion is K! and hydrogen sulfite is HSO3"; KHSO3.
Lead(IV) is Pb4! and sulfide is S2"; PbS2.
Gold(III) is Au3! and carbonate is CO32"; Au2(CO3)3.
Zinc ion is Zn2! and perchlorate is ClO4"; Zn(ClO4)2.
5.82 a.
b.
c.
d.
e.
Fe(NO3)3
Cu(HCO3)2
Sn(SO3)2
Ba(H2PO4)2
Cd(ClO)2
5.83 a. Ions: Au3! and Cl" : AuCl3
b. Ions: Pb4! and O2" : PbO2
c. Ions: Ag! and Cl" : AgCl
40
b. calcium phosphate
d. Pb4! is the lead(IV) ion; lead(IV) chloride.
f. Sn2! is the tin(II) ion; tin(II) sulfate.
b. barium nitrate
d. lithium perchlorate
f. sodium hydrogen phosphate
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Names and Formulas of Compounds
d. Ions: Ca2! and N3" : Ca3N2
e. Ions: Cu! and P3" : Cu3P
f. Ions: Cr2! and Cl" : CrCl2
5.84 a. SnO2
d. CrI3
b. Fe2S3
e. Li3N
c. PbS2
f. Au2O
5.85 a. magnesium oxide
b. Cr(HCO3)3 is chromium(III) hydrogen carbonate or chromium (III) bicarbonate.
c. manganese(III) chromate
5.86 a. copper(I) sulfide
b. iron(II) phosphate
c. calcium hypochlorite
5.87 a.
b.
c.
d.
e.
f.
1N and 3Cl
1S and 2Cl
2N and 1O
2F
1P and 5Cl
2P and 5O
5.88 a.
b.
c.
d.
e.
f.
1C and 4Br
1S and 6Fl
2Br
2N and 4O
1S and 2O
1C and 2S
5.89 a.
b.
c.
d.
1C and 1O
di(2) and penta(5)
di(2) and 1S
1S and di(2)Cl
: CO
: P2O5
: H2S
: SCl2
5.90 a.
b.
c.
d.
1Si and di(2)O
1C and tetra(4)Br
1S and tri(3)O
2N and 1O
: SiO2
: CBr4
: SO3
: N2O
5.91 a.
b.
c.
d.
e.
f.
ionic, iron(III) chloride
ionic, sodium sulfate
covalent, 2N and 1O : dinitrogen oxide
covalent, fluorine (named as the element)
covalent, 1P and 5Cl : phosphorus pentachloride
covalent, 1C and 4F : carbon tetrafluoride
5.92 a.
b.
c.
d.
e.
f.
ionic, aluminum carbonate
covalent, sulfur hexafluoride
covalent, diatomic element : bromine
ionic, magnesium nitride
covalent, sulfur dioxide
ionic, chromium(III) phosphate
:
:
:
:
:
:
nitrogen trichloride
sulfur dichloride
dinitrogen monoxide
fluorine (named as the element)
phosphorus pentachloride
diphosphorus pentoxide
:
:
:
:
:
:
carbon tetrabromide
sulfur hexafluoride
bromine
dinitrogen tetroxide
sulfur dioxide
carbon disulfide
5.93 a. Tin(II) is Sn2!; carbonate is CO32". With charges balanced, the formula is SnCO3.
b. Lithium is Li!; phosphide is P3". Using three Li! for charge balance, the formula is Li3P.
c. Silicon has 4 valence electrons to share with 4 chlorine atoms to give SiCl4.
41
47374_05_p33-42.qxd 2/9/07 7:52 AM Page 42
Chapter 5
d. Iron(III) is Fe3!; sulfide is S2". Charge is balanced with 2 Fe3! and 3 S2" to write the
formula Fe2S3.
e. Carbon has 4 valence electrons to form 2 double bonds with 2 oxygen atoms to give the
formula CO2.
f. Calcium is Ca2!; Bromide is Br". With charges balanced, the formula is CaBr2.
5.94 a. Na2CO3
d. Cu3N
b. NO2
e. K3PO4
c. Al(NO3)3
f. PbO2
5.95 Na2S has two Na! ions to every S2" ion.
1 S2" ion
4.8 $ 1022 Na! ions $
# 2.4 $ 1022 S2" ions
2 Na! ions
5.96 Mg3N2 has three Mg2! ions to every two N3" ions.
2 N3" ions
4.8 $ 1022 Mg2! ions $
# 3.2 $ 1022 S2" ions
3 Mg2!ions
5.97 The valence electrons are the electrons in the highest energy level lost or gained in the formation
of ionic compounds.
5.98 The octet rule states that a representative element will gain or lose electrons until the atom has 8
electrons in its outermost electron level.
5.99 Elements in Group 2A (2) will lose 2 electrons to attain an octet; elements in Group 6A (16) will
gain 2 electrons to attain an octet. Both either gain or lose 2 electrons.
5.100 a.
b.
c.
d.
e.
The correct name of the compound is calcium nitrate.
Copper(II) oxide is CuO. Cu2O is copper(I) oxide.
It is not necessary to put the symbol for potassium in brackets; the correct formula is K2CO3.
Na2S is sodium sulfide. Sodium sulfate is Na2SO4.
The silver ion is Ag!. The formula for silver sulfate is Ag2SO4.
5.101 Formula of Compound
FeSO4
SiO2
NH4NO3
Al2(SO4)3
Co2S3
Type of Compound
Name of Compound
ionic
covalent
ionic
ionic
ionic
iron(II) sulfate
silicon dioxide
ammonium nitrate
aluminum sulfate
cobalt (III) sulfide
5.102 a. Ar
c. Kr
b. Kr
5.103 Compounds with a metal and nonmetal are classified as ionic; two nonmetals as covalent.
a. ionic, lithium oxide
b. covalent, dinitrogen oxide
c. covalent, carbon tetrafluoride
d. covalent, dichlorine oxide
e. ionic, magnesium fluoride
f. covalent, carbon monoxide
g. ionic, calcium chloride
h. ionic, potassium phosphate
5.104 a.
c.
e.
g.
i.
k.
42
iron(II) chloride
nitrogen
phosphorus trichloride
lead(IV) chloride
nitrogen dioxide
barium nitrate
b.
d.
f.
h.
j.
l.
dichlorine heptoxide
calcium phosphate
aluminum nitrate
magnesium carbonate
tin(II) sulfate
copper(II) sulfide