Chapter 14:
The Elements: The First Four Main Groups
1. Why do atomic radii decrease from left to right across a period, even though
subsequent elements have more electrons?
a. Greater nuclear charge is experienced across the period, pushing electrons farther
from the nucleus.
b. Lesser nuclear charge is experienced across the period, pulling electrons in closer to
the nucleus.
c. Greater nuclear charge is experienced across the period, pulling electrons in closer to
the nucleus.
d. Lesser nuclear charge is experienced across the period, pushing electrons farther from
the nucleus.
Answer:
C
2. What is a formal anhydride of an acid?
a. The molecule obtained by adding two hydrogen atoms and one oxygen atom.
b. The molecule obtained after adding water to the metal oxide.
c. The molecule obtained by striking out two hydrogen atoms and one oxygen atom.
d. None of the above.
Answer:
C
3. How is elemental hydrogen produced?
a. By refining fossil fuels through the re-forming and shift reactions.
b. Through the electrolysis of water.
c. Both of the above.
d. None of the above; rather, it is obtained through the dehydration of water.
Answer:
C
4. Why are hydrides powerful oxidizing agents?
a. Because they are easy to reduce.
b. Because the hydride ion is highly polarizable.
c. Because hydrogen is most stable in the 1+ oxidation state.
d. They are not; rather, they are powerful reducing agents.
Answer:
D
5. Why are the alkali metals not found in their free states in nature?
a. They are too easily oxidized.
b. They are too easily reduced.
c. They combine too readily with other metals.
d. They are only trace elements on the planet.
Answer:
A
6.
a.
b.
c.
What makes sodium compounds so useful indusrtially?
They are inexpensive.
They are routinely soluble in water.
They are generally unreactive.
d. Both a and b above.
Answer:
D
7. In what state do the alkaline earth metals exist in nature?
a. As free elements.
b. in compounds as +1 cations.
c. in compounds as +2 cations.
d. in compounds as +1 or +2 cations, depending on the compound.
Answer:
C
8.
a.
b.
c.
d.
Why are magnesium compounds such as magnesium ion so soluble in water?
Because of the 2+ charge of the magnesium ion.
Because of the small size of the magnesium ion.
Because of the excellent charge-to-size ratio of the magnesium ion.
They are not; rather, magnesium oxide and other magnesium compounds typically
have low solubility in water.
Answer:
D
9. What is the naturally occurring source of boron?
a. Borax and kernite ores.
b. Bauxite ores.
c. Gray-black allotropic boron deposits.
d. As a by-product of aluminum refining.
Answer:
A
10. Why do boron and aluminum oxides act as Lewis acids?
a. Because the boron and aluminum atoms form tetrahedra when in complexes.
b. Because the boron and aluminum atoms are tri-valent.
c. Because the boron and aluminum atoms have incomplete octets of electrons.
d. They do not; rather, they act as Lewis bases.
Answer:
C
11. What common factor do all the boranes possess?
a. They all are composed only of boron and oxygen.
b. They all are composed only of boron and hydrogen.
c. They are all reactive species that behave as micrometals.
d. Nothing; the boranes are a wide series of compounds with widely differeing
elemental compositions and reactivities.
Answer:
B
12. Why can’t a singly bonded carbon atom act as a Lewis acid, as a singly bonded
silicon atom can?
a. Because carbon can expand its valence shell, unlike silicon.
b. Because carbon forms multiple bonds.
c. Because carbon can not expand its valence shell as silicon can.
d. It can, both carbon and silicon can act as Lewis acids.
Answer:
C
13. What do buckminsterfullerene and diamond have in common?
a. Both have the same number of atoms in their unit cell.
b. Both have the same lattice structure.
c. Both are allotropic forms of carbon.
d. Nothing.
Answer:
C
14. What is the acid anhydride of carbonic acid?
a. Carbon dioxide.
b. Carbon monoxide.
c. Carbon black.
d. Any allotropic form of carbon.
Answer:
A
15. How is the rigid, regular structure of silicate glasses produced?
a. By slow thermal expansion upon cooling from the molten state.
b. By rapid cooling from the molten to the solid state.
c. By the addition of salts to the structure.
d. There is no regular structure produced; rather, glasses have an amorphous structure.
Answer:
D