Chapter 2 – Atoms, Molecules, and Ions
Prof. Kweyete
1. Determine the number of protons, electrons, and neutrons in the
followings:
a) 65 Zn => 30p, 35n, 30eb) cobalt-60 => 27p, 33n, 27ec) sodium
=> 11p, 12n, 11e52
3+
d) Cr
=> 24p, 28n, 21e130 e)
I
=> 53p, 77n, 54e2. For each of the following elements, write its chemical symbol or name,
and indicate the type and group to which it belongs:
a) potassium
K, metal, group 1
b) arsenic
As, semimetal, group 5
c) iodine
I, nonmetal, group 7
d) iron
Fe, metal, transition metal
e) Ca
Calcium, metal, group 2
3. Determine the empirical formulas for the following compounds:
a) C6H10O2 C3H5O
b) Si3O9
SiO3
c) N2O4
NO2
e) CH4
CH4
f) S4N4
SN
4. Predict the
a) Al
b) OH
c) O
d) SO4
e) HSO3
f) ClO
charges of the ions of the followings:
(+3)
(-1)
(-2)
(-2)
(-1)
(-1)
5. Predict the empirical formula for the ionic compounds formed by
following:
a) Ca2+ , PO43Ca3(PO4)2
+
b) K , NO3
KNO3
3+
c) Al , OH
Al(OH)3
2+
d) Ba , HCO3
Ba(HCO3)2
6. Predict whether each of the following compound is molecular (M) or
ionic (I):
a) NaClO (I)
e) AlN (I)
b) NOCl (M)
c) CoCO3 (I)
d) SCl2 (M)
7. Give names or chemical formulas for the following acids:
a) H2S hydrosulfuric acid
b) Nitric acid HNO3
c) perbromic acid HBrO4
d) HI hydroiodic acid
e) H2SO3
Sulfurous acid
g) Acetic acid HC2H3O2
f) HClO2
h) HCN
Chlorous acid
hydrocyanic acid
8. Provide names or chemical formulas for the following:
a) Cr(NO3)3 Chromium(III)nitrate
c) Cr2O3 Chromium(III) oxide
e) Lead(IV) acetate Pb(C2H3O2)4
g) S4N4 tetrasulfur tetra nitride
b) silver nitrate
AgNO3
d) Fe(NO2)2 Iron(II) nitrite
f) dinitrogen trioxide
N 2O 3
h) KClO potassium hypochlorite
9. Give a chemical formula or name for the followings:
a) chlorate ion ClO3b) oxide ion O-2
c) barium ion Ba+2
d) hydrogencarbonate ion HCO3e) HSO3bisulfite ion
f) S2- sulfide ion
g) Fe3+
Iron(III) ion
h) H3O+ hydronium ion
10. Naturally occurring magnesium has the following isotopic abundances:
Isotope
Abundance
Mass
Mg-24
78.70%
23.98504
Mg-25
10.13%
24.98584
Mg-26
11.17%
25.98259
Calculate the average atomic mass of magnesium.
(0.787)(23.98504) + (0.1013)(24.98584) + (0.1117)(25.98259) = 24.31 amu
11. What is the difference between hydroacid and oxyacid? Give two
examples of each. Hydroacids do not have oxygen in their formula
(HCl, HBr) Oxyacids contain oxygen in their formula (HNO3, H2SO4)