Chapter 2 Chang - Chemistry

Chapter 2: 13, 15, 33, 45, 46, 47, 48, 49, 50, 53, 59, 73

13. Lower number is the atomic number (# protons) and upper value is the mass number

(protons+neutrons)

He = 2 protons and 3-2 = 1 neutron He = 2 protons and 4-2 = 2 neutrons

Mg = 12 protons and 24-12 = 12 neutrons Mg = 12 protons and 25-12 = 13 neutrons

Ti = 22 protons and 48-22 = 26 neutrons Br = 35 protons and 79-35 = 44 neutrons

Pt = 78 protons and 195-78 =117 neutrons

15. The symbol is given by the atomic number (Z) a. Na b. Ni

33. A positive ion loses electrons, and a negative ion gains electrons. the proton # are assigned
by the element chosen, and does not change when an ion is formed.

Ion Protons Electrons

(=atomic #)
Na+ 11
Ca2+ 10

20 18
Al3+ 13
Fe2+ 26 10

I- 53 24

F- 9 54

S2- 16 10

O2- 8 18

N3- 7 10

10

45. Metal+nonmetal = ionic compound two nonmetals = molecular compound

SiCl4 = molecular LiF = ionic BaCl2 = ionic
B2H6 = molecular KCl = ionic C2H4 = molecular

46. Metal+nonmetal = ionic compound two nonmetals = molecular compound

CH4 = molecular NaBr = ionic BaF2 = ionic CCl4 = molecular
ICl = molecular CsCl = ionic NF3 = molecular

47. a. Na2CrO4 sodium chromate (ionic)
b. K2HPO4 potassium hydrogen phosphate (ionic)
c. HBr(g) hydrogen bromide (ionic)

d. HBr(aq) hydrobromic acid (acid)
e. Li2CO3 lithium carbonate (ionic)
f. K2Cr2O7 potassium dichromate (ionic)
g. NH4NO2 ammonium nitrite (ionic)
h. PF3 phosphorus trifluoride (molecular)
i. PF5 phosphorous pentafluoride (molecular)
j. P4O6 tetraphosphorous hexoxide (molecular)
k. CdI2 cadmium iodide (ionic)
l. SrSO4 strontium sulfate (ionic)
m. Al(OH)3 aluminum hydroxide (ionic)
n. Na2CO3·10 H2O sodium carbonate decahydrate (ionic)

48. a. KClO potassium hypochlorite (all of these are ionic)
b. Ag2CO3
c. FeCl2 silver(I) carbonate (*Ag=+1 always, no RN)
d. KMnO4
e. CsClO3 iron(II) chloride
f. HIO
g. FeO potassium permanganate
h. Fe2O3
i. TiCl4 cesium chlorate
j. NaH
k. Li3N hydrogen hypoiodite if g, hypoiodous acid if aq
l. Na2O
m. Na2O2 iron(II) oxide
n. FeCl3·6 H2O
iron(III) oxide

titanium(IV) chloride

sodium hydride

lithium nitride

sodium oxide (* peroxide = O22-)

sodium peroxide
iron(III) chloride hexahydrate

49. a. rubidium nitrite RbNO2 (ionic)
(ionic)
b. potassium sulfide K2S (ionic)
(ionic)
c. perbromic acid HBrO4 (aq) (ionic)
(molecular)
d. magnesium phosphate Mg3(PO4)2 (molecular)
(ionic)
e. calcium hydrogen phosphate CaHPO4 (ionic)
f. boron trichloride BCl3 (ionic)
(ionic)
g. iodine heptafluoride IF7

h. ammonium sulfate (NH4)2SO4

i. silver perchlorate AgClO4

j. iron (III) chromate Fe2(CrO4)3

k. calcium sulfate dihydrate CaSO4·2 H2O

50. a. copper(I) cyanide CuCN (ionic)
b. strontium chlorite
c. perchloric acid Sr(ClO2)2 (ionic)
d. hydroiodic acid
e. disodium ammonium phosphate HClO4 (aq) (acid)
HI (aq) (acid)

Na2(NH4)PO4 (ionic) (* breaks common rules)

f. lead(II) carbonate PbCO3 (ionic)
g. tin(II) fluoride SnF2 (ionic)
h. tetraphosphorus decasulfide P4S10 (molecular)
i. mercury(II) oxide HgO (ionic)
j. mercur (I) iodide Hg2I2 (ionic) (* Hg22+ )
k. cobalt(II) chloride hexahydrate CoCl2· 6 H2O (ionic)

53. a. To be neutral: # protons = # electrons A, F, G
Negative charge: #protons < # electrons (gain e-) B, E
Positive charge: #protons > # electrons (lose e-) C, D

Symbols: A= B B= N C= K D = Zn E = Br F= B G= F

59. B Fe P Au Rn
Symbol 5 26 15 79 86
Protons 6 28 16 117 136
Neutrons 5 24 18 79 86
Electrons 0 2+ -3 0 0

Net charge

73. Anion Formula Name
HCO3- Mg(HCO3)2 magnesium bicarbonate
Cation
Mg2+ Cl– SrCl2 strontium chloride
Sr2+ NO2- Fe(NO2)3 iron(III) nitrite
Fe3+ ClO3- Mn(ClO3)2
Mn2+ Br- manganese (II) chlorate
Sn4+ PO43- SnBr4 tin(IV) bromide
Co2+ Co3(PO4)2
I- cobalt(II) phosphate
Hg Hg2I2 mercury(I) iodide
Cu+ CO32- Cu2CO3 copper(I) carbonate
Li+ N3–
Li3N lithium nitride
Al3+ S2-
Al2S3 aluminum sulfide