Chapter 2 Atoms, Molecules, and Ions

1
Chapter 2Atoms, Molecules,and Ions
2
How many neutrons are there in an atom of 14C?

• 6
• 8
• 12
• 14

3
Correct Answer

• 6
• 8
• 12
• 14

14
Mass number
C
6
Atomic number
The difference between the mass number and the
atomic number is the number of neutrons (14 ? 6)
8.
4
An isotope of Cr3 ion containing 24 protons and
27 neutrons would contain ___ electrons.

• 21
• 24
• 27
• 3

5
Correct Answer

• 21
• 24
• 27
• 3

The 3 charge indicates there are 3 more protons
than electrons 24 ? 3 21
6
A hypothetical element has two isotopes. One of
the isotopes has an abundance of 75.0 and a
relative mass of 12.0 amu, while the other has an
abundance of 25.0 and a relative mass of 14.0
amu. The atomic mass of this hypothetical element
is

• 12.5 amu.
• 13.0 amu.

• 13.5 amu.
• 13.8 amu.

7
Correct Answer

• 12.5 amu.
• 13.0 amu.

• 13.5 amu.
• 13.8 amu.

Atomic mass (0.750)(12.0 amu) (0.250)(14.0
amu) Atomic mass 9.0 amu 3.5 amu 12.5 amu
8
Chlorine has two isotopes, 35Cl (75.78 abundant)
and 37Cl (24.22 abundant). How many different
molar masses are possible for a Cl2 molecule?

• 2
• 3
• 4
• 5

9
Correct Answer

• 2
• 3
• 4
• 5

35Cl2 70 amu 35Cl37Cl 72 amu 37Cl2 74 amu
10
Which of the following species has the greatest
number of electrons?

• Cl?
• Ca2
• P3?
• K
• Ar

11
Correct Answer

• Cl?
• Ca2
• P3?
• K
• Ar

K has 19 electrons all the other species listed
have only 18 electrons.
12
If you have equal masses of the following metals,
which will have the largest number of atoms?

• Pb, 207.2 g/mol
• Au, 197 g/mol
• Ag, 107.9 g/mol
• Cu, 63.54 g/mol
• Fe, 55.85 g/mol

13
If you have equal masses of the following metals,
which will have the largest number of atoms?

• Pb, 207.2 g/mol
• Au, 197 g/mol
• Ag, 107.9 g/mol
• Cu, 63.54 g/mol
• Fe, 55.85 g/mol

14
Which combination is likely to produce an ionic
compound?

• C and H
• S and Cl
• Ca and F
• Br and I
• Xe and F

15
Which combination is likely to produce an ionic
compound?

• C and H
• S and Cl
• Ca and F
• Br and I
• Xe and F

16
The compound, CuSO4, is called

• Calcium sulfide
• Carbon sulfide
• Calcium sulfite
• Calcium sulfate
• Copper sulfate

17
Correct Answer

• Calcium sulfide
• Carbon sulfide
• Calcium sulfite
• Calcium sulfate
• Copper sulfate

The compound is ionic, derived from the
copper(II) cation (Cu2) and the sulfate anion
(SO42?).
18
The correct name for the compound, MgC2 is

• Carbon magneside
• Magnesium carbide
• Magnesium carbonate
• Manganese dicarbide
• Magnesium dicarbide

19
Correct Answer

• Carbon magneside
• Magnesium carbide
• Magnesium carbonate
• Manganese dicarbide
• Magnesium dicarbide

In this unusual ionic compound, the cation is
magnesium cation (Mg2) and the anion is carbide
or acetylide (C22?).
20
The simplest chemical formula for the binary
ionic compound CaxNy is

• Ca2N
• Ca2N3
• Ca3N2
• Ca3N

21
Correct Answer

• Ca2N
• Ca2N3
• Ca3N2
• Ca3N

Ca loses two electrons to become Ca2, while N
gains three electrons to become N3?. To be
neutral, positive charges and negative charges
have to balance.
22
The ion Cr2O72? is known as

• Chromos
• Chromite
• Chromate
• Dichromate
• Bichromite

23
Correct Answer

• Chromos
• Chromite
• Chromate
• Dichromate
• Bichromite

Dichromate solutions are a deep orange color.
24
The acid HClO3 is known as

• Perchloric acid
• Chloric acid
• Chlorous acid
• Hypochlorous acid
• Hydrochloric acid

25
Correct Answer

• Perchloric acid
• Chloric acid
• Chlorous acid
• Hypochlorous acid
• Hydrochloric acid

26
The molecular compound N2O4 is named

• Nitrogen oxide
• Oxygen nitride
• Dinitrogen quartoxide
• Dinitrogen tetroxide
• Nitrous oxide

27
Correct Answer

• Nitrogen oxide
• Oxygen nitride
• Dinitrogen quartoxide
• Dinitrogen tetroxide
• Nitrous oxide

Remember the vowel A on the prefix tetra- is
dropped because oxide starts with the vowel O.