Section 11.1
Classification of Matter
1. (Exercises 1 and 2) Classify each of the following materials as an element, compound,
heterogeneous mixture, or homogeneous mixture: a. vodka, b. sodium chloride (NaCl),
c. diatomic oxygen, d. potato salad, e. copper wire.
a. Vodka is a homogeneous mixture of alcohol and water.
b. NaCl is a compound composed of two different elements.
c. O2 is an element whose molecules are composed of two identical atoms.
d. Potato salad is a heterogeneous mixture of several finely cut foods.
e. Copper wire is composed of a single element.
2. (Exercises 5 and 6) Refer to Fig. 11.5. Would the resulting solution be
saturated or unsaturated if 30 g of KCl were stirred into 100 g of water at
80°?
The solution would be unsaturated. According to the figure, about 50 g
of KCl is needed per 100 g of water at 80° to form a saturated solution.
So, with only 30 g available, the solution will be unsaturated.
Section 11.2Discovery of the Elements
3. (Exercises 11 and 12) Give the name or symbol for each of the following elements.
| a. chromium | b. lead | c. iodine | d. Ba | e. F | f. Ag |
a. The chemical symbol for chromium is Cr.
b. The chemical symbol for lead is Pb.
c. The chemical symbol for iodine is I.
d. Ba is the chemical symbol for barium.
e. F is the chemical symbol for fluorine.
f. Ag is the chemical symbol for silver.
Section 11.4The Periodic Table
4. (Exercises 21 and 22) Arrange the following pairs of elements in order
of increasing
metallic character: a. Ge and Mn, b. Cl and Ar,
c. Sn and I, d. O and S.
The general rules for metallic character indicate that this property
increases as you go down any group in the periodic table, and decreases
as you move across (from left to right) any period. This indicates that:
a. Mn is more metallic than Ge;
b. Cl is more metallic than Ar;
c. Sn is more metallic than I;
d. S in more metallic than O.
5. (Exercises 23 and 24, 25 and 26) Arrange the elements F, Cl, Br, I, and At according to:
a. the relative size of their atoms.
b. the ionization energy of their atoms.
These elements are all in Group 7A in the periodic table, so we can determine
the trends in properties of these atoms quite easily.
a. The relative size of the atoms increases as we go down any group in the periodic table,
as shown in Figure 11.20 in the textbook. The order of increasing size for the atoms of
these elements will be: F, Cl, Br, I, and At.
b. The ionization energy decreases as more shells are added
to the atom, as shown in Figure 11.21 in the textbook. In this case, more shells are being
added as we go down the groups in the periodic table, so the order of increasing
ionization energy would be: At, I, Br, Cl, F.
Section 11.5Naming Compounds
6. (Exercises 29 and 30) Give the preferred names for the following compounds:
| a. CH4 | b. KF | c. SO3 | d. ZnSO4 | e. H2CO3 |
a. CH4 is a compound with a special name and is always called methane.
b. KF is a metal-nonmetal compound and is named potassium fluoride.
c. SO3 is a nonmetal-nonmetal compound and is called sulfur trioxide.
d. ZnSO4 is a metal-polyatomic ion (SO42-)
compound and so is named zinc sulfate.
e. H2CO3 is hydrogen combined with a polyatomic ion
to form an acid, and it is named carbonic acid.
Section 11.6Groups of Elements
7. (Exercises 31 and 32) Given the fact that magnesium forms the following
compounds Mg(NO
3)
2, MgCl
2, and
Mg
3(PO
4)
2, write the chemical formulas for:
a. calcium nitrate;
b. calcium chloride;
c. calcium phosphate.
Both magnesium and calcium are in group 2A. Because the chemical compounds
formed by all of the elements in the same column of the periodic table will
be similar, a comparison of the compounds formed by magnesium will tell us
the structure of the chemical formulas for the compounds formed by calcium.
These compounds of calcium will be:
a. Ca(NO3)2
b. CaCl2
c. Ca3(PO4)2
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