Chapter 2: Atoms, Molecules, and Ions
1. The first people to attempt to explain why chemical changes occur were
A)
alchemists
B)
metallurgists
C)
physicians
D)
physicists
E)
the Greeks
2. The Greeks proposed that matter consisted of four fundamental substances:
A)
fire, earth, water, air
B)
fire, metal, water, air
C)
earth, metal, water, air
D)
atoms, fire, water, air
E)
atoms, metal, fire, air
3. The first chemist to perform truly quantitative experiments was
A)
Paracelsus
B)
Boyle
C)
Priestly
D)
Bauer
E)
Lavoisier
4. The scientist who discovered the law of conservation of mass and is also called the father of
modern chemistry is
A)
Proust
B)
Boyle
C)
Priestly
D)
Bauer
E)
Lavoisier
5. Which of the following pairs of compounds can be used to illustrate the law of multiple
proportions?
A)
NH4 and NH4Cl
B)
ZnO2 and ZnCl2
C)
H2O and HCl
D)
NO and NO2
E)
CH4 and CO2
6. Which of the following pairs can be used to illustrate the law of multiple proportions?
A)
SO and SO2
B)
CO and CaCO3
C)
H2O and C12H22O11
D)
H2SO4 and H2S
E)
KCl and KClO2
7. According to the law of multiple proportions:
A)
If the same two elements form two different compounds, they do so in the same
ratio.
B)
It is not possible for the same two elements to form more than one compound.
C)
The ratio of the masses of the elements in a compound is always the same.
D)
The total mass after a chemical change is the same as before the change.
E)
None of these.
8. A sample of chemical X is found to contain 5.0 grams of oxygen, 10.0 grams of carbon, and
20.0 grams of nitrogen. The law of definite proportion would predict that a 70 gram sample
of chemical X should contain how many grams of carbon?
A)
5.0 grams
B)
7.0 grams
C)
10. grams
D)
15 grams
E)
20 grams
9. Consider the following two compounds: H2O and H2O2 . According to the
law of multiple proportions, the ratio of hydrogen atoms per gram of oxygen in H2O to
hydrogen atoms per gram of oxygen in H2O2 is
A)
1:1
B)
2:1
C)
1:2
D)
2:2
E)
4:1
10. Which of the following statements from Dalton’s atomic theory is no longer true, according
to modern atomic theory?
A)
Elements are made up of tiny particles called atoms.
B)
Atoms are not created or destroyed in chemical reactions.
C)
All atoms of a given element are identical.
D)
Atoms are indivisible in chemical reactions.
E)
All of these statements are true according to modern atomic theory.
11. How many of the following postulates of Dalton’s atomic theory are still scientifically
accepted?
I.
All atoms of the same element are identical.
II.
Compounds are combinations of different atoms.
III.
A chemical reaction changes the way atoms are grouped
together.
IV.
Atoms are indestructible.
A)
0
B)
1
C)
2
D)
3
E)
4
12. The chemist credited for inventing a set of symbols for writing elements and a system for
writing the formulas of compounds (and for discovering selenium, silicon, and thorium) is
A)
Boyle
B)
Lavoisier
C)
Priestly
D)
Berzelius
E)
Dalton
13. Avogadro’s hypothesis states that:
A)
Each atom of oxygen is 16 times more massive than an atom of hydrogen.
B)
A given compound always contains exactly the same proportion of elements by
mass.
C)
When two elements form a series of compounds, the ratios of masses that combine
with 1 gram of the first element can always be reduced to small whole numbers.
D)
At the same temperature and pressure, equal volumes of different gases contain an
equal number of particles.
E)
Mass is neither created nor destroyed in a chemical reaction.
14. The first scientist to show that atoms emit any negative particles was
A)
J. J. Thomson
B)
Lord Kelvin
C)
Ernest Rutherford
D)
William Thomson
E)
John Dalton
15. Many classic experiments have given us indirect evidence of the nature of the atom. Which
of the experiments listed below did not give the results described?
A)
The Rutherford experiment proved the Thomson “plum-pudding” model of the
atom to be essentially correct.
B)
The Rutherford experiment was useful in determining the nuclear charge on the
atom.
C)
Millikan’s oil-drop experiment showed that the charge on any particle was a simple
multiple of the charge on the electron.
D)
The electric discharge tube proved that electrons have a negative charge.
E)
All of the above experiments gave the results described.
16. The scientist whose alpha-particle scattering experiment led him to conclude that the
nucleus of an atom contains a dense center of positive charge is
A)
J. J. Thomson
B)
Lord Kelvin
C)
Ernest Rutherford
D)
William Thomson
E)
John Dalton
17. Alpha particles beamed at thin metal foil may
A)
pass directly through without changing direction
B)
be slightly diverted by attraction to electrons
C)
be reflected by direct contact with nuclei
D)
A and C
E)
A, B, and C
18. Which one of the following statements about atomic structure is false?
A)
An atom is mostly empty space.
B)
Almost all of the mass of the atom is concentrated in the nucleus.
C)
The protons and neutrons in the nucleus are very tightly packed.
D)
The number of protons and neutrons is always the same in the neutral atom.
E)
All of the above statements (A-D) are true.
19. If the Thomson model of the atom had been correct, Rutherford would have observed:
A)
Alpha particles going through the foil with little or no deflection.
B)
Alpha particles greatly deflected by the metal foil.
C)
Alpha particles bouncing off the foil.
D)
Positive particles formed in the foil.
E)
None of the above observations is consistent with the Thomson model of the atom.
20. Which statement is not correct?
A)
The mass of an alpha particle is 7300 times that of the electron.
B)
An alpha particle has a 2+ charge.
C)
Three types of radioactive emission are gamma rays, beta rays, and alpha particles.
D)
A gamma ray is high-energy light.
E)
There are only three types of radioactivity known to scientists today.
21. Rutherford’s experiment was important because it showed that:
A)
Radioactive elements give off alpha particles.
B)
Gold foil can be made to be only a few atoms thick.
C)
A zinc sulfide screen scintillates when struck by a charged particle.
D)
The mass of the atom is uniformly distributed throughout the atom.
E)
An atom is mostly empty space.
22. Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of
bromine-79 contains
A)
35 protons, 44 neutrons, 35 electrons
B)
34 protons and 35 electrons, only
C)
44 protons, 44 electrons, and 35 neutrons
D)
35 protons, 79 neutrons, and 35 electrons
E)
79 protons, 79 electrons, and 35 neutrons
23. Which of the following atomic symbols is incorrect?
A)
B)
C)
D)
E)
24. The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-
185 has in its nucleus
A)
75 protons, 75 neutrons
B)
75 protons, 130 neutrons
C)
130 protons, 75 neutrons
D)
75 protons, 110 neutrons
E)
not enough information
25. Which among the following represent a set of isotopes? Atomic nuclei containing:
I.
20 protons and 20 neutrons
II.
21 protons and 19 neutrons
III.
22 neutrons and 18 protons
IV.
20 protons and 22 neutrons
V.
21 protons and 20 neutrons
A)
I, II, III
B)
III, IV
C)
I, V
D)
I, IV and II, V
E)
No isotopes are indicated.
26. By knowing the number of protons a neutral atom has, you should be able to determine
A)
the number of neutrons in the neutral atom
B)
the number of electrons in the neutral atom
C)
the name of the atom
D)
two of the above
E)
none of the above
27. Which of the following statements are true of uranium-238?
I.
Its chemical properties will be exactly like those of uranium-235.
II.
Its mass will be slightly different from that of an atom of uranium–
235.
III.
It will contain a different number of protons than an atom of uranium-
235.
IV.
It is more plentiful in nature than uranium-235.
A)
III, IV
B)
I, II, III
C)
I, II, IV
D)
II, III, IV
E)
all of these
28. An isotope, X, of a particular element has an atomic number of 15 and a mass number of 31.
Therefore:
A)
X is an isotope of phosphorus.
B)
X has 16 neutrons per atom.
C)
X has an atomic mass of 30.973.
D)
A and B.
E)
A, B, and C.
29. Which of the following statements is true?
A)
Ions are formed by adding or removing protons or electrons.
B)
Scientists believe that solids are mostly open space.
C)
Heating water with a Bunsen burner results in a 2:1 mixture of hydrogen and
oxygen gases.
D)
At least two of the above statements (A-C) are true.
E)
All of the statements (A-C) are false.
30. The number of neutrons in an atom is the same for all neutral atoms of that element.
31. The number of electrons in an atom is the same for all neutral atoms of that element.
32. has
A)
20 protons, 20 neutrons, and 18 electrons
B)
22 protons, 20 neutrons, and 20 electrons
C)
20 protons, 22 neutrons, and 18 electrons
D)
22 protons, 18 neutrons, and 18 electrons
E)
20 protons, 20 neutrons, and 22 electrons
33. Which of the following statements is (are) true?
A)
and have the same number of neutrons.
B)
and are isotopes of each other because their mass numbers are the same.
C)
has the same number of electrons as .
D)
A and B
E)
A and C
34. A species with 12 protons and 10 electrons is
A)
Ne2+
B)
Ti2+
C)
Mg2+
D)
Mg
E)
Ne2–
35. The numbers of protons, neutrons, and electrons in K+ are:
A)
20 p, 19 n, 19 e
B)
20 p, 19 n, 20 e
C)
19 p, 20 n, 20 e
D)
19 p, 20 n, 19 e
E)
19 p, 20 n, 18 e
36. An ion is formed
A)
By either adding or subtracting protons from the atom.
B)
By either adding or subtracting electrons from the atom
C)
By either adding or subtracting neutrons from the atom.
D)
All of the above are true.
E)
Two of the above are true.
37. The formula of water, H2O, suggests:
A)
There is twice as much mass of hydrogen as oxygen in each molecule.
B)
There are two hydrogen atoms and one oxygen atom per water molecule.
C)
There is twice as much mass of oxygen as hydrogen in each molecule.
D)
There are two oxygen atoms and one hydrogen atom per water molecule.
E)
None of these.
38. All of the following are true except:
A)
Ions are formed by adding electrons to a neutral atom.
B)
Ions are formed by changing the number of protons in an atom’s nucleus.
C)
Ions are formed by removing electrons from a neutral atom.
D)
An ion has a positive or negative charge.
E)
Metals tend to form positive ions.
39. Which of the following are incorrectly paired?
A)
K, alkali metal
B)
Ba, alkaline earth metal
C)
O, halogen
D)
Ne, noble gas
E)
Ni, transition metal
40. Which of the following are incorrectly paired?
A)
Sr, alkaline earth metal
B)
Ta, transition metal
C)
F, halogen
D)
H, noble gas
E)
Ru, transition metal
41. Which of the following are incorrectly paired?
A)
Phosphorus, Pr
B)
Palladium, Pd
C)
Platinum, Pt
D)
Lead, Pb
E)
Potassium, K
42. Which of the following are incorrectly paired?
A)
Copper, Cu
B)
Carbon, C
C)
Cobalt, Co
D)
Calcium, Ca
E)
Cesium, Ce
43. Which of the following are incorrectly paired?
A)
Antimony, Sb
B)
Silicon, Si
C)
Silver, Ag
D)
Argon, Ar
E)
Astatine, As
44. All of the following are characteristics of metals except:
A)
good conductors of heat
B)
malleable
C)
ductile
D)
often lustrous
E)
tend to gain electrons in chemical reactions
45. All of the following are characteristics of nonmetals except:
A)
poor conductors of electricity
B)
often bond to each other by forming covalent bonds
C)
tend to form negative ions in chemical reactions with metals
D)
appear in the upper left-hand corner of the periodic table
E)
do not have a shiny (lustrous) appearance
46. Which of the following has 61 neutrons, 47 protons, and 46 electrons?
A)
Pm
B)
Ag+
C)
Pd–
D)
Cd+
E)
Ag
47. How many protons and electrons does the most stable ion for oxygen have?
# protons
# electrons
A)
10 p 8 e
B)
8 p 6 e
C)
6 p 8 e
D)
8 p 8 e
E)
8 p 10 e
48. You are given a compound with the formula MCl2, in which M is a metal. You are told that
the metal ion has 26 electrons. What is the identity of the metal?
A)
Fe
B)
Al
C)
Zn
D)
Co
E)
Ni
49. Which of the following names is incorrect?
A)
cobalt(II) chloride
B)
magnesium oxide
C)
aluminum(III) oxide
D)
diphosphorus pentoxide
E)
All of the above names are correct.
50. Which of the following pairs is incorrect?
A)
iodine trichloride, ICl3
B)
phosphorus pentoxide, P2O5
C)
ammonia, NH3
D)
sulfur hexafluoride, SF6
E)
All of the above pairs are correct.
51. The correct name for LiCl is
A)
lithium monochloride
B)
lithium(I) chloride
C)
monolithium chloride
D)
lithium chloride
E)
monolithium monochloride