Atoms Molecules and Ions

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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
ANS: E
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
ANS: A
3. The first chemist to perform truly quantitative experiments was
A) Paracelsus
B) Boyle
C) Priestly
D) Bauer
E) Lavoisier
ANS: B
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
ANS: E
KEY: Chemistry | general chemistry | general concepts | matter | Law of Conservation of
Mass
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
ANS: D
| atomic theory of matter | Dalton's atomic theory
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
ANS: A
| atomic theory of matter
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.
ANS: E
| atomic theory of matter | Dalton's atomic theory
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
ANS: E
| atomic theory of matter | Dalton's atomic theory
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
ANS: B
| atomic theory of matter | Dalton's atomic theory
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.
ANS: C
| atomic theory of matter | Dalton's 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)
B)
C)
D)
E)
0
1
2
3
4
ANS: C
| atomic theory of matter | Dalton's atomic theory
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
ANS: D
| chemical substance | chemical formula
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.
ANS: D
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
ANS: A
REF: 2.4
| atomic theory of matter | structure of the atom | discovery of electron
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.
ANS: A
REF: 2.4
| atomic theory of matter | structure of the atom
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
ANS: C
REF: 2.4
| atomic theory of matter | structure of the atom | nuclear model of atom
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
ANS: E
REF: 2.4
| atomic theory of matter | structure of the atom | nuclear model of atom
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.
ANS: D
REF: 2.4
| atomic theory of matter | structure of the atom | nuclear model of atom
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.
ANS: A
REF: 2.4
| atomic theory of matter | structure of the atom | nuclear model of 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.
ANS: E
| atomic theory of matter
REF: 2.4
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.
ANS: E
REF: 2.4
| atomic theory of matter | structure of the atom | nuclear model of atom
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
ANS: A
REF: 2.5
| atomic theory of matter | nuclear structure
23. Which of the following atomic symbols is incorrect?
A)
B)
C)
D)
E)
ANS: E
REF: 2.5
| atomic theory of matter | structure of the atom
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
ANS: D
| atomic theory of matter | isotope
REF: 2.5
25. Which among the following represent a set of isotopes? Atomic nuclei containing:
I.
II.
III.
IV.
V.
A)
B)
C)
D)
E)
20 protons and 20 neutrons
21 protons and 19 neutrons
22 neutrons and 18 protons
20 protons and 22 neutrons
21 protons and 20 neutrons
I, II, III
III, IV
I, V
I, IV and II, V
No isotopes are indicated.
ANS: D
| atomic theory of matter | isotope
REF: 2.5
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
ANS: D
REF: 2.5
| atomic theory of matter | nuclear structure
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)
B)
C)
D)
E)
III, IV
I, II, III
I, II, IV
II, III, IV
all of these
ANS: C
| atomic theory of matter | isotope
REF: 2.5
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.
ANS: D
| atomic theory of matter | isotope
REF: 2.5
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.
ANS: B
REF: 2.5
30. The number of neutrons in an atom is the same for all neutral atoms of that element.
ANS: F
| atomic theory of matter | isotope
REF: 2.5
31. The number of electrons in an atom is the same for all neutral atoms of that element.
ANS: T
REF: 2.5
| atomic theory of matter | nuclear structure
32.
has
A) 20 protons, 20 neutrons, and 18 electrons
B)
C)
D)
E)
22 protons, 20 neutrons, and 20 electrons
20 protons, 22 neutrons, and 18 electrons
22 protons, 18 neutrons, and 18 electrons
20 protons, 20 neutrons, and 22 electrons
ANS: A
| atomic theory of matter | isotope
REF: 2.6
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
ANS: E
| atomic theory of matter | isotope
REF: 2.6
34. A species with 12 protons and 10 electrons is
A) Ne2+
B) Ti2+
C) Mg2+
D) Mg
E) Ne2–
ANS: C
REF: 2.6
| atomic theory of matter | nuclear structure
35. The numbers of protons, neutrons, and electrons in
A)
B)
C)
D)
E)
K+ are:
20 p, 19 n, 19 e
20 p, 19 n, 20 e
19 p, 20 n, 20 e
19 p, 20 n, 19 e
19 p, 20 n, 18 e
ANS: E
REF: 2.6
| atomic theory of matter | nuclear structure
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.
ANS: B
REF: 2.6
| chemical substance | chemical formula | ionic substance
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.
ANS: B
REF: 2.6
| chemical substance | chemical formula | molecular substance
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.
ANS: B
REF: 2.6
| chemical substance | chemical formula | ionic substance
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
ANS: C
| periodic table | group
REF: 2.7
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
ANS: D
| periodic table | group
REF: 2.7
41. Which of the following are incorrectly paired?
A) Phosphorus, Pr
B) Palladium, Pd
C) Platinum, Pt
D) Lead, Pb
E) Potassium, K
ANS: A
| periodic table
REF: 2.7
42. Which of the following are incorrectly paired?
A) Copper, Cu
B) Carbon, C
C) Cobalt, Co
D) Calcium, Ca
E) Cesium, Ce
ANS: E
| periodic table
REF: 2.7
43. Which of the following are incorrectly paired?
A) Antimony, Sb
B) Silicon, Si
C) Silver, Ag
D) Argon, Ar
E) Astatine, As
ANS: E
| periodic table
REF: 2.7
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
ANS: E
| periodic table | metal
REF: 2.7
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
ANS: D
| periodic table | nonmetal
REF: 2.7
46. Which of the following has 61 neutrons, 47 protons, and 46 electrons?
A)
Pm
B)
Ag+
C)
Pd–
D)
E)
Cd+
Ag
ANS: B
| periodic table
REF: 2.7
47. How many protons and electrons does the most stable ion for oxygen have?
# protons # electrons
A)
B)
C)
D)
E)
10 p
8p
6p
8p
8p
8e
6e
8e
8e
10 e
ANS: E
| periodic table | group
REF: 2.8
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
ANS: E
REF: 2.7
| chemical substance | chemical formula | ionic substance
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.
ANS: C
REF: 2.8
| chemical substance | nomenclature of simple compound
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.
ANS: B
REF: 2.8
| chemical substance | nomenclature of simple compound | binary molecular compound
51. The correct name for LiCl is
A) lithium monochloride
B) lithium(I) chloride
C) monolithium chloride
D) lithium chloride
E) monolithium monochloride
ANS: D
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
52. How many oxygen atoms are there in one formula unit of Ca3(PO4)2?
A) 2
B) 4
C) 6
D) 8
E) none of these
ANS: D
REF: 2.8
| chemical substance | chemical formula | ionic substance
53. How many oxygen atoms are there in 4 formula units of Al2(CO3)3?
A) 9
B) 24
C) 36
D) 13
E) 39
ANS: C
REF: 2.8
| chemical substance | chemical formula | ionic substance
54. The correct name for FeO is
A) iron oxide
B) iron(II) oxide
C) iron(III) oxide
D) iron monoxide
E) iron(I) oxide
ANS: B
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
55. The correct name for Ca2+ is
A) calcium
B) calcium(II) ion
C) calcium ion
D) calcium(I) ion
E) monocalcium ion
ANS: C
REF: 2.8
| chemical substance | chemical formula | ionic substance
56. The correct name for V3+ is
A) vanadide
B) vanadite ion
C) vanadium(III) ion
D) vanadium(V) ion
E) trivanadium ion
ANS: C
REF: 2.8
| chemical substance | chemical formula | ionic substance
57. The correct name for P3– is
A) phosphide ion
B) phosphorus ion
C) phosphorus(III) ion
D) phospho(III) ion
E) phosphite
ANS: A
REF: 2.8
| chemical substance | chemical formula | ionic substance
58. What is the subscript of barium in the formula of barium sulfate?
A) 1
B) 2
C) 3
D) 4
E) 0
ANS: A
REF: 2.8
| chemical substance | chemical formula | ionic substance
59. The formula for calcium bisulfate is
A) Ca(SO4)2
B) CaS2
C) Ca(HSO4)2
D) Ca2HSO4
E) Ca2S
ANS: C
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
60. The formula for sodium dihydrogen phosphate is
A) NaH2PO4
B) Na(HPO4)2
C) NaHPO4
D) Na2HPO4
E) Na2H2PO4
ANS: A
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
61. Which of the following is incorrectly named?
A) Pb(NO3)2, lead(II) nitrate
B) NH4ClO4, ammonium perchlorate
C) PO43–, phosphate ion
D) Mg(OH)2, magnesium hydroxide
E) NO3–, nitrite ion
ANS: E
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
62. Which of the following is incorrectly named?
A) SO32–, sulfite ion
B) S2O32–, thiosulfate ion
C) PO43–, phosphate ion
D) ClO3–, chlorite ion
E) CN–, cyanide ion
ANS: D
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
63. All of the following are in aqueous solution. Which is incorrectly named?
A) H2SO4, sulfuric acid
B) H2CO3, carbonic acid
C) H3PO4, phosphoric acid
D) HCN, cyanic acid
E) HCl, hydrochloric acid
ANS: D
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
64. All of the following are in aqueous solution. Which is incorrectly named?
A) HC2H3O2, acetic acid
B) HBr, bromic acid
C) H2SO3, sulfurous acid
D) HNO2, nitrous acid
E) HClO3, chloric acid
ANS: B
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
65. Which of the following pairs is incorrect?
A) NH4Br, ammonium bromide
B) K2CO3, potassium carbonate
C) BaPO4, barium phosphate
D) CuCl, copper(I) chloride
E) MnO2, manganese(IV) oxide
ANS: C
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
66. Which of the following name(s) is(are) correct?
1. sulfide, S2–
2. ammonium chloride, NH4Cl
3. acetic acid, HC2H3O2
4. barium oxide, BaO
A)
B)
C)
D)
E)
all
none
1, 2
3, 4
1, 3, 4
ANS: A
REF: 2.8
| chemical substance | nomenclature of simple compound
67. Which metals form cations with varying positive charges?
A) transition metals
B) Group 1 metals
C) Group 2 metals
D) Group 3 metals
E) metalloids
ANS: A
REF: 2.8
| chemical substance | chemical formula | ionic substance
68. Three samples of a solid substance composed of elements A and Z were prepared. The first
contained 4.31 g A and 7.70 g Z. The second sample was 35.9% A and 64.1% Z. It was
observed that 0.718 g A reacted with Z to form 2.00 g of the third sample. Show that these
data illustrate the law of definite composition.
ANS:
Sample (1): ratio of masses (Z/A) = 7.70/4.13 = 1.785
Sample (2): ratio of masses (Z/A) = 64.1/35.9 = 1.785
Sample (3): ratio of masses (Z/A) = (2.00-0.718)/0.718 = 1.785
These three samples thus illustrate that a given compound always contains the same
proportion of elements by mass.
See Sec. 2.2 of Zumdahl, Chemistry.
| atomic theory of matter | Dalton's atomic theory
69. Explain how Dalton’s atomic theory accounts for:
a) the law of conservation of mass
b) the law of definite composition
c) the law of multiple proportion
ANS:
(a) Chemical reactions involve only reorganization of the atoms.
(b) A given compound always has the same relative numbers and types of atoms.
(c) Since, according to Dalton, atoms of a given element are identical and a given compound
always has the same relative numbers and types of atoms, the observation of different mass
ratio combinations of the same elements to give different compounds supports the law of
multiple proportion.
See Sec. 2.3 of Zumdahl, Chemistry.
| atomic theory of matter | Dalton's atomic theory
70. Complete the following table.
Symbol
206
# Protons
# Neutrons
31
38
52
75
# Electrons
Net Charge
Pb
Mn2+
3+
54
30
2+
ANS:
Symbol
# Protons
# Neutrons
Pb
82
124
82
0
Ga3+
31
38
28
3+
Te2–
52
75
54
2-
Mn2+
25
29
23
2+
206
# Electrons Net Charge
REF: 2.5
| atomic theory of matter | nuclear structure
71. Complete the following table.
Symbol
Number of protons
Number of neutrons
Number of electrons
Atomic number
Mass number
Net charge
ANS:
69Ga3+
34
46
2–
Symbol
69Ga3+
80
Se2–
Number of protons
31
34
Number of neutrons
38
46
Number of electrons
28
36
Atomic number
31
34
Mass number
69
80
Net charge
+3
2–
REF: 2.5
| atomic theory of matter | nuclear structure
72. Arsenopyrite is a mineral containing As, Fe, and S. Classify each element as metal,
nonmetal, or metalloid.
ANS:
As = metalloid, Fe = metal, S = nonmetal
REF: 2.7
| periodic table
73. Write the symbol for each of the following elements.
a)
silver
_____________
b)
calcium
_____________
c)
iodine
_____________
d)
copper
_____________
e)
phosphorus
_____________
ANS:
a) Ag, b) Ca, c) I, d) Cu, e) P
REF: 2.7
| periodic table
74. Write the names of the following compounds:
a)
FeSO4
________________
b)
NaC2H3O2
________________
c)
KNO2
________________
d)
Ca(OH)2
________________
e)
NiCO3
________________
ANS:
a) iron(II) sulfate
b) sodium acetate
c) potassium nitrite
d) calcium hydroxide
e) nickel(II) carbonate
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
75. Write the chemical formulas for the following compounds or ions.
a)
nitrate ion
_________
b)
aluminum oxide
_________
c)
ammonium ion
_________
d)
perchloric acid
_________
e)
copper(II) bromide
_________
ANS:
a) NO3–
b) Al2O3
c) NH4+
d) HClO4
REF: 2.8
| chemical substance | chemical formula | ionic substance
76. How many atoms (total) are there in one formula unit of Ca3(PO4)2?
ANS:
13
REF: 2.8
| chemical substance | chemical formula | ionic substance
Name the following compounds:
77. Al2(SO4)3
ANS:
aluminum sulfate
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
78. NH4NO3
ANS:
ammonium nitrate
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
79. NaH
ANS:
e) CuBr2
sodium hydride
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
80. K2Cr2O7
ANS:
potassium dichromate
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
81. CCl4
ANS:
carbon tetrachloride
REF: 2.8
| chemical substance | nomenclature of simple compound | binary molecular compound
82. AgCl
ANS:
silver chloride
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
83. CaSO4
ANS:
calcium sulfate
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
84. HNO2
ANS:
nitrous acid
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
85. N2O3
ANS:
dinitrogen trioxide
REF: 2.8
| chemical substance | nomenclature of simple compound | binary molecular compound
86. SnI2
ANS:
tin(II) iodide
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
Write the formula for:
87. sodium thiosulfate
ANS:
Na2S2O3
REF: 2.8
| chemical substance | chemical formula | ionic substance
88. iron(III) oxide
ANS:
Fe2O3
REF: 2.8
| chemical substance | chemical formula | ionic substance
89. dichlorine heptoxide
ANS:
Cl2O7
REF: 2.8
| chemical substance | chemical formula | molecular substance
90. cobalt(II) chloride
ANS:
CoCl2
REF: 2.8
| chemical substance | chemical formula | ionic substance
91. aluminum hydroxide
ANS:
Al(OH)3
REF: 2.8
| chemical substance | chemical formula | ionic substance
92. sulfurous acid
ANS:
H2SO3
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
93. nitric acid
ANS:
HNO3
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
94. phosphoric acid
ANS:
H3PO4
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
95. acetic acid
ANS:
CH3COOH
REF: 2.8
| chemical substance | nomenclature of simple compound | acid
96. phosphorus trichloride
ANS:
PCl3
REF: 2.8
| chemical substance | nomenclature of simple compound | binary molecular compound
97. Which of these statements is a consequence (follows from) the Law of Definite Proportion?
A) All samples of chlorine contain 35Cl and 37Cl in the same (definite) ratio.
B) The mass of oxygen that is combined with a fixed mass of nitrogen in each of the
binary nitrogen oxides can be expressed as a ratio of small whole numbers.
C) The atomic masses of all of the elements in the periodic table have fixed values.
D) The % lead by mass in the compound galena is the same for all pure samples
obtained from any source.
E) None of these is correct
ANS: D
| atomic theory of matter | Dalton's atomic theory
98. Which of these statements is a consequence (follows from) the Law of Multiple
Proportions?
A) All samples of chlorine contain 35Cl and 37Cl in the same (definite) ratio.
B) The mass of oxygen that is combined with a fixed mass of nitrogen in each of the
binary nitrogen oxides can be expressed as a ratio of small whole numbers.
C) The atomic masses of all of the elements in the periodic table have fixed values.
D) The % lead by mass in the compound galena is the same for all pure samples
obtained from any source.
E) None of these is correct
ANS: B
| atomic theory of matter | Dalton's atomic theory
99. Which of the following elements does NOT have a symbol taken from a LATIN name for
the element or one of its compounds?
A) iron
D) potassium
B) copper
E) titanium
C) sodium
ANS: E
| periodic table
REF: 2.7
100. Which of the following statements is FALSE?
A) sulfur does not conduct electricity
D) silicon is a metalloid
B) gold is malleable
E) hydrogen is a non-metal
C) germanium is a metal
ANS: C
| periodic table |
REF: 2.7
101. Which of the following ions is NOT likely to form from the appropriate atom?
A) C4+
D) Ti4+
3B) As
E) Na+
C) Mg2+
ANS: A
| periodic table | group
REF: 2.8
102. How many protons, neutrons and electrons, in that order are present in the anion formed by
one atom of 125I?
A) 53, 74, 54
D) 53, 72, 54
B) 52, 72, 53
E) 54, 74, 54
C) 54, 72, 53
ANS: D
REF: 2.8
| atomic theory of matter | isotope | periodic table
103. How many protons, neutrons and electrons, in that order are present in the anion formed by
one atom of 79Se?
A) 34, 34, 45
D) 34, 45, 36
B) 34, 45, 34
E) 36, 45, 36
C) 32, 45, 34
ANS: D
REF: 2.8
| atomic theory of matter | isotope | periodic table
104. Which statement is INCORRECT?
A) An atom of 60Zn has an equal number of protons and neutrons
B) An atom of 50Mn has an equal number of electrons and neutrons
C) An atom of 18O has an equal number of protons and neutrons
D) An atom of 41K has an equal number of protons and electrons
E) An atom of 238U contains 146 neutrons.
ANS: C
| atomic theory of matter | isotope |
REF: 2.5
105. Which of the following atoms, isotopes or ions contains 23 protons, 18 electrons and 27
neutrons?
A) 45Co5+
D) 41Kr5B) 50Kr
E) 50V550 5+
C) V
ANS: C
REF: 2.8
| atomic theory of matter | isotope | periodic table
106. Which of the following compounds is incorrectly named?
A) Mg(OH)2 is magnesium dihydroxide
D) K3PO4 is potassium phosphate
B) CaO is calcium oxide
E) MgSO3 is magnesium sulfite
C) NH4NO3 is ammonium nitrate
ANS: A
REF: 2.8
| chemical substance | nomenclature of simple compound | ionic compound
Chapter 2: Atoms, Molecules, and Ions
1. The scientist who determined the magnitude of the electric charge of the electron was
A)
John Dalton
D)
Henry Moseley
B)
Robert Millikan
E)
J. Burdge
C)
J. J. Thomson
Ans: B
2. When J. J. Thomson discovered the electron, what physical property of the electron did he
measure?
A)
its charge, e
D)
its mass, m
B)
its charge-to-mass ratio, e/m
E)
its atomic number, Z
C)
its temperature, T
Ans: B
3. What name is given to the concept that different samples of a given compound always contain
the same elements in the same mass ratio?
A)
Ration Law
D)
Law of Definite Proportions
B)
Law of Equality
E)
2nd Law of thermodynamics
st
C)
1 Law of Thermodynamics
Ans: D
4. Which field of study made a big contribution toward understanding the composition of the atom?
A)
Electricity
D)
Electrochemistry
B)
Radiation
E)
Quantum Mechanics
C)
Solution Chemistry
Ans: B
5. Which of the following is a type of radioactive radiation which has no charge and are unaffected
by external electric or magnetic fields?
A)  rays
B)  rays
C)  rays
D)  rays
E)  rays
Ans: C
6. Which of the following is a type of radioactive radiation that consists of positively charged particles and is deflected away from the positively charged plate?
A)  rays
B)  rays
C)  rays
D)  rays
E)  rays
Ans: A
7. Which of the following is a type of radioactive radiation that consists of electrons and is deflected away from the negatively charged plate?
A)  rays
B)  rays
C)  rays
D)  rays
E)  rays
Ans: B
8. Which of these scientists developed the nuclear model of the atom?
A)
John Dalton
D)
Henry Moseley
B)
Robert Millikan
E)
Ernest Rutherford
C)
J. J. Thomson
Ans: E
9. Rutherford's experiment with alpha particle scattering by gold foil established that
A)
protons are not evenly distributed throughout an atom.
B)
electrons have a negative charge.
C)
electrons have a positive charge.
D)
atoms are made of protons, neutrons, and electrons.
E)
protons are 1840 times heavier than electrons.
Ans: A
10. J. J. Thomson studied cathode ray particles (electrons) and was able to measure the
mass/charge ratio. His results showed that
A)
the mass/charge ratio varied as the cathode material was changed.
B)
the charge was always a whole-number multiple of some minimum charge.
C)
matter included particles much smaller than the atom.
D)
atoms contained dense areas of positive charge.
E)
atoms are largely empty space.
Ans: B
11. Who is credited with measuring the mass/charge ratio of the electron?
A) Dalton
B) Chadwick
C) Thomson
D) Millikan
E) Rutherford
Ans: C
12. Who is credited with first measuring the charge of the electron?
A) Dalton
B) Gay-Lussac
C) Thomson
D) Millikan
Ans: D
E) Rutherford
13. Millikan's oil-drop experiment
A)
established the charge on an electron.
B)
showed that all oil drops carried the same charge.
C)
provided support for the nuclear model of the atom.
D)
suggested that some oil drops carried fractional numbers of electrons.
E)
suggested the presence of a neutral particle in the atom.
Ans: A
14. Who is credited with discovering the atomic nucleus?
A) Dalton
B) Gay-Lussac
C) Thomson
D)
Ans: E
Chadwick
E) Rutherford
15. Rutherford bombarded gold foil with alpha () particles and found that a small percentage of
the particles were deflected. Which of the following was not accounted for by the model he
proposed for the structure of atoms?
A)
the small size of the nucleus
B)
the charge on the nucleus
C)
the total mass of the atom
D)
the existence of protons
E)
the presence of electrons outside the nucleus
Ans: C
16. Which one of the following statements about atoms and subatomic particles is correct?
A)
Rutherford discovered the atomic nucleus by bombarding gold foil with electrons.
B)
The proton and the neutron have identical masses.
C)
The neutron's mass is equal to that of a proton plus an electron.
D)
A neutral atom contains equal numbers of protons and electrons.
E)
An atomic nucleus contains equal numbers of protons and neutrons.
Ans: D
17. Who discovered the subatomic particle having a neutral charge called neutron?
A) Millikan
B) Dalton
C) Chadwick
D) Rutherford
E) Thomson
Ans: C
18. What term is used to represent the number of protons in the nucleus of each atom of an element and is equal to the number of electrons outside the nucleus?
A)
Isotope number
D)
Atomic number
B)
Mass number
E)
Atomic mass units
C)
Mass-to-charge ratio
Ans: D
19. What term is used to represent the total number of neutrons and protons in the nucleus of
each atom of an element?
A)
Isotope number
D)
Atomic number
B)
Mass number
E)
Atomic mass units
C)
Mass-to-charge ratio
Ans: B
20. Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81,
. Select the combination which lists the correct atomic number, neutron number,
and mass number, respectively.
A) 35, 46, 81
B) 35, 81, 46
C) 81, 46, 35
D) 46, 81, 35
E) 35, 81, 116
Ans: A
21. Atoms X, Y, Z, and R have the following nuclear compositions:
Which two are isotopes?
A) X & Y
B) X & R
Ans: E
C) Y & R
D)
Z&R
E) X & Z
22. Atoms of the same element with different mass numbers are called
A) ions.
B) neutrons.
C) allotropes.
D) chemical families.
Ans: E
23. How many neutrons are there in an atom of lead whose mass number is 208?
A) 82
B) 126
C) 208
D) 290
E) None of the above
Ans: B
E) isotopes.
24. An atom of the isotope sulfur-31 consists of how many protons, neutrons, and electrons?
(p = proton, n = neutron, e = electron)
A)
15 p, 16 n, 15 e
D)
32 p, 31 n, 32 e
B)
16 p, 15 n, 16 e
E)
16 p, 16 n, 15 e
C)
16 p, 31 n, 16 e
Ans: B
25. Give the number of protons (p), electrons (e), and neutrons (n) in one atom of chlorine-37.
A)
37 p, 37 e, 17 n
D)
37 p, 17 e, 20 n
B)
17 p, 17 e, 37 n
E)
17 p, 37 e, 17 n
C)
17 p, 17 e, 20 n
Ans: C
26. Two isotopes of an element differ only in their
A)
symbol.
B)
atomic number.
C)
atomic mass.
Ans: C
27. A magnesium ion, Mg2+, has
A)
12 protons and 13 electrons.
B)
24 protons and 26 electrons.
C)
12 protons and 10 electrons.
Ans: C
28. An aluminum ion, Al3+, has:
A)
13 protons and 13 electrons
B)
27 protons and 24 electrons
C)
16 protons and 13 electrons
Ans: D
29. An oxide ion, O2–, has:
A)
8 protons and 10 electrons
B)
10 protons and 8 electrons
C)
8 protons and 9 electrons
Ans: A
30. A sulfide ion, S2–, has:
A)
16 protons and 16 electrons
B)
32 protons and 16 electrons
C)
16 protons and 14 electrons
Ans: D
D)
E)
number of protons.
number of electrons.
D)
E)
24 protons and 22 electrons.
12 protons and 14 electrons.
D)
E)
13 protons and 10 electrons
10 protons and 13 electrons
D)
E)
8 protons and 7 electrons
10 protons and 7 electrons
D)
E)
16 protons and 18 electrons
32 protons and 18 electrons
31. How many protons and electrons are present in one Br– ion?
A)
35 p, 35 e
D)
35 p,
B)
80 p, 81 e
E)
80 p,
C)
35 p, 34 e
Ans: D
36 e
34 e
32. The elements in a column of the periodic table are known as
A) metalloids.
B) a period.
C) noble gases.
D)
Ans: D
a group.
E)
nonmetals.
33. Which of these materials are usually poor conductors of heat and electricity?
A)
metals
D)
alkaline earth metals
B)
metalloids
E)
alkali metals
C)
nonmetals
Ans: C
34. Which of these elements is most likely to be a good conductor of electricity?
A) N
B) S
C) He
D) Cl
E) Fe
Ans: E
35. Which of the following elements are the least reactive?
A)
alkali metals
D)
alkaline earth metals
B)
noble gases
E)
metalloids
C)
halogens
Ans: B
36. Which of the following is a non-metal?
A)
lithium, Li, Z = 3
B)
bromine, Br, Z = 35
C)
mercury, Hg, Z = 80
Ans: B
37. Which of the following is a metal?
A)
nitrogen, N, Z = 7
B)
phosphorus, P, Z = 15
C)
arsenic, Z = 33
Ans: D
38. Which of the following is a metalloid?
A)
carbon, C, Z = 6
B)
sulfur, S, Z = 16
C)
germanium, Ge, Z = 32
Ans: C
D)
E)
bismuth, Bi, Z = 83
sodium, Na, Z = 11
D)
E)
thallium, Tl, Z = 81
silicon, Si, Z = 14
D)
E)
iridium, Z = 77
bromine, Br, Z = 35
39. A row of the periodic table is called a
A) group
B) period
C) isotopic mixture
Ans: B
D) family
E)
subshell
40. Silicon, which makes up about 25% of Earth's crust by mass, is used widely in the modern electronics industry. It has three naturally occurring isotopes, 28Si, 29Si, and 30Si. Calculate the atomic
mass of silicon.
Isotope
28
Si
29Si
30
Si
A)
29.2252 amu
B)
28.9757 amu
C)
28.7260 amu
Ans: D
Isotopic Mass (amu)
27.976927
28.976495
29.973770
Abundance %
92.23
4.67
3.10
D)
E)
28.0855 amu
27.9801 amu
41. Lithium forms compounds which are used in dry cells and storage batteries and in
high-temperature lubricants. It has two naturally occurring isotopes, 6Li (isotopic mass =
6.015121 amu) and 7Li (isotopic mass = 7.016003 amu). Lithium has an atomic mass of 6.9409
amu. What is the percent abundance of lithium-6?
A) 92.50%
B) 86.66%
C) 46.16%
D) 7.503%
E) 6.080%
Ans: D
42. What is the name used to define a mass which is exactly equal to 1/12 the mass of one carbon-12 atom?
A)
Isotope number
D)
Atomic number
B)
Mass number
E)
Atomic mass units
C)
Mass-to-charge ratio
Ans: E
43. Which of the following cannot exist as a homonuclear diatomic molecule?
A) hydrogen
B) phosphorus
C) fluorine
D) nitrogen
E)
Ans: B
44. Which is the correct definition of a diatomic molecule?
A)
A molecule which contains two or more of the same atoms
B)
A molecule which contains two or more different atoms
C)
A molecule which contains two identical atoms
D)
A molecule which contains two different atoms
E)
c and d
Ans: E
45. Which is the correct definition of a polyatomic molecule?
A)
A molecule which contains two or more of the same atoms
B)
A molecule which contains two or more different atoms
C)
a and b
D)
A molecule which contains two identical atoms
E)
A molecule which contains two different atoms
Ans: C
oxygen
46. Which is the correct definition of a heteronuclear diatomic molecule?
A)
A molecule which contains two or more of the same atoms
B)
A molecule which contains two or more different atoms
C)
a and b
D)
A molecule which contains two identical atoms
E)
A molecule which contains two different atoms
Ans: E
47. What represents the exact number of atoms of each element in a molecule?
A)
Chemical formula
D)
Molecular formula
B)
Compound
E)
Atomic formula
C)
Constitutional formula
Ans: D
48. Which of the following are allotropes?
A)
diamond and graphite
B)
hydrogen and deuterium
C)
bromine and chlorine
Ans: A
D)
E)
hydrogen and oxygen
None of the above
49. Which of these elements is chemically similar to magnesium?
A) sulfur
B) calcium
C) iron
D) nickel
E)
Ans: B
potassium
50. Which of these elements is chemically similar to oxygen?
A) sulfur
B) calcium
C) iron
D) nickel
Ans: A
potassium
E)
51. Which of these elements is chemically similar to potassium?
A) calcium
B) arsenic
C) phosphorus
D) cerium
Ans: E
E)
cesium
52. Which, if any, of the following elements do not occur in the major classes of organic compounds?
A)
H
B)
C
C)
N
D)
O
E)
All the above elements occur in the major classes of organic compounds.
Ans: E
53. What name is given to a class of compounds that generally do not contain carbon?
A)
Acarbonic compounds
D)
Inorganic compounds
B)
Carbonic compounds
E)
Aldehyde compounds
C)
Organic compounds
Ans: D
54. Which of the following is the empirical formula for hexane, C6H14?
A) C12H28
B) C6H14
C) C3H7
D) CH2.3
E) C0.43H
Ans: C
55. Which of the following is a molecular formula for CH?
A) C2H6
B) C3H9
C) C4H10
D) C6H6
Ans: D
56. What is the name of PCl3?
A)
phosphorus chloride
B)
phosphoric chloride
C)
phosphorus trichlorate
Ans: E
D)
E)
E) None of the answers are correct.
trichlorophosphid
phosphorus trichloride
57. The compound, P4S10, is used in the manufacture of safety matches. What is its name?
A)
phosphorus sulfide
D)
tetraphosphorus decasulfide
B)
phosphoric sulfide
E)
phosphorus sulfite
C)
phosphorus decasulfide
Ans: D
58. Diiodine pentaoxide is used as an oxidizing agent that converts carbon monoxide to carbon
dioxide. What is its chemical formula?
A) I2O5
B) IO5
C) 2IO5
D) I5O2
E) (IO5)2
Ans: A
59. What is the name of P4Se3?
A)
phosphorus selenide
B)
phosphorus triselenide
C)
tetraphosphorus selenide
Ans: E
60. What is the name of ClO-?
A) hypochlorite
B) chlorate
Ans: A
D)
E)
C)
chlorite
61. What is the formula for the permanganate ion?
A) MnO2B) MnO4C) MgO42D)
Ans: B
phosphoric selenide
tetraphosphorus triselenide
D) perchlorate
Mn2O7-
E)
E) perchlorite
MgO22-
62. Tetrasulfur dinitride decomposes explosively when heated. What is its formula?
A) S2N4
B) S4N2
C) 4SN2
D) S4N
E) S2N
Ans: B
63. An anion is defined as
A)
a charged atom or group of atoms with a net negative charge.
B)
a stable atom.
C)
a group of stable atoms.
D)
an atom or group of atoms with a net positive charge.
E)
neutral.
Ans: A
64. Which one of these species is an ion?
A) B3+
B) NaCl
C) He
D)
Ans: A
14C
E) None of the above
65. Which of these pairs of elements would be most likely to form an ionic compound?
A) P and Br
B) Cu and K
C) C and O
D) O and Zn
E) Al and Rb
Ans: D
66. Which pair of elements would be most likely to form an ionic compound?
A) P and Br
B) Zn and K
C) F and Al
D) C and S
E) Al and Rb
Ans: C
67. What is the formula for the ionic compound formed by calcium ions and nitrate ions?
A) Ca3N2
B) Ca(NO3)2
C) Ca2NO3
D) Ca2NO2
E) CaNO3
Ans: B
68. What is the formula for the ionic compound formed by calcium and selenium?
A) CaSe
B) Ca2Se
C) CaSe2
D) Ca3Se
E) CaSe3
Ans: A
69. Which is the correct formula for copper (II) phosphate?
A) Cu2PO4
B) Cu3(PO4)2
C) Cu2PO3
D) Cu(PO4)2
Ans: B
E) Cu(PO3)2
70. The chemical name for ClO3– is “chlorate ion”. What is the common name for HClO3?
A)
hydrochloric acid
D)
chlorous acid
B)
chloroform
E)
chloric acid
C)
hydrogen trioxychloride
Ans: E
71. The formula for magnesium sulfate is
A) MnS
B) MgS
C) MnSO3
Ans: D
72. The formula for sodium sulfide is
A) NaS
B) K2S
C) NaS2
Ans: D
D) MgSO4
D) Na2S
73. The chemical formula for iron (II) nitrate is
A) Fe2(NO3)3
B) Ir(NO2)2
C) Fe2N3
Ans: D
E)
MnSO4
E) SeS
D) Fe(NO3)2
E)
Fe(NO2)2
74. Which one of the following formulas of ionic compounds is the least likely to be correct?
A) NH4Cl
B) Ba(OH)2
C) Na2SO4
D) Ca2NO3
E) Cu(CN)2
Ans: D
75. What is the formula for lead (II) oxide?
A) PbO
B) PbO2
C) Pb2O
Ans: A
D) PbO4
E)
Pb2O3
76. Potassium permanganate is a strong oxidizer that reacts explosively with easily oxidized materials. What is its formula?
A) KMnO3
B) KMnO4
C) K2MnO4
D) K(MnO4)2
E) K2Mn2O7
Ans: B
77. Ferric oxide is used as a pigment in metal polishing. Which of the following is its formula?
A) FeO
B) Fe2O
C) FeO3
D) Fe2O5
E) Fe2O3
Ans: E
78. What is the name of Mn(CO3)2?
A)
manganese carbide
B)
magnesium (IV) carbonate
C)
manganese (II) carbonate
Ans: E
D)
E)
magnesium (II) carbonate
manganese (IV) carbonate
79. Iron (III) chloride hexahydrate is used as a coagulant for sewage and industrial wastes. What is
its formula?
A)
Fe(Cl·6H2O)3
D)
Fe3Cl(H2O)6
B)
Fe3Cl·6H2O
E)
FeCl3·6H2O
C)
FeCl3(H2O)6
Ans: E
80. Which of the following is the oxoanion of bromine called the bromate ion?
A) BrO3B) BrO32C) BrO42D) BrO2E) BrOAns: A
81. The mass of a neutron is equal to the mass of a proton plus the mass of an electron.
Ans: False
82. All neutral atoms of tin have 50 protons and 50 electrons.
Ans: True
83. Copper (Cu) is a transition metal.
Ans: True
84. Lead (Pb) is a main-group element.
Ans: True
85. Ionic compounds may carry a net positive or negative charge.
Ans: False
86. When an alkali metal combines with a non-metal, a covalent bond is normally formed.
Ans: False
87. The empirical formula of C6H6 is CH.
Ans: True
88. Almost all the mass of an atom is concentrated in the nucleus.
Ans: True
89. When a beam of alpha particles passes between two electrically charged plates, the beam is
deflected toward the positive plate.
Ans: False
90. J. J. Thomson suggested the name “radioactivity” to describe the spontaneous emission of particles and/or radiation.
Ans: False
91. An allotrope is a mixture of forms of the same compound that exist in the same physical state
under the same conditions of temperature and pressure.
Ans: False
92. An ionizable hydrogen atom is a hydrogen atom that separates from the molecule when the
molecule is dissolved in a solution and becomes a hydrogen ion, H+.
Ans: True
93. What is the law that describes different samples of a given compound that always contain the
same elements in the same mass ratio?
Ans: law of definite proportions
94. What is the law of conservation of mass?
Ans: Matter can be neither created nor destroyed.
95. How many neutrons are in 13C?
Ans: 7
96. What name is given to the simplest organic compounds which only contain carbons and hydrogens?
Ans: hydrocarbons
97. What is the name of Cu2O?
Ans: Copper (I) oxide
98. What is the formula for sodium dichromate?
Ans: Na2Cr2O7
99. What is the name given for the elements in Group 1A in the periodic table?
Ans: Alkali metals
100. What is the name given for the elements in Group 7A in the periodic table?
Ans: Halogens
101. Which group is given the name chalcogens?
Ans: Group 6A
102. What are the three types of radiation produced by the decay of substances like uranium?
Ans: Alpha, beta, and gamma radiation
103. Define ion.
Ans: An ion is an atom or group of atoms that has a net positive or negative charge.
104. Fill in the blank spaces and write out all the symbols in the left hand column in full, in the form
(i.e., include the appropriate values of Z and A as well as the correct symbol X).
Symbol
# protons
# neutrons
# electrons
…
17
18
…
Au
…
118
…
…
…
20
20
Ans:
Cl
Au
Ca
17
79
20
18
118
20
17
79
20
105. ________________ is the emission and transmission of energy through space in the form of
waves.
Ans: Radiation
106. _____________ is the negatively charged plate connected to a high-voltage source.
Ans: Cathode
107. ______________ coined the term radioactivity to describe the spontaneous emission of particles and/or radiation.
Ans: Marie Curie
108. ______________ are electrons that are deflected away from negatively charged plates.
Ans:  particles
109. ______________ are atoms that have the same atomic number (Z) but different mass numbers
(A).
Ans: Isotopes
110. _____________ have properties that are intermediate between those of metals and nonmetals.
Ans: Metalloids
111. ____________ are the name given for the elements in Group VIIIA.
Ans: Noble gases
112. _____________ compounds consist of two different elements.
Ans: Binary
113. _________________ is defined as a mass exactly equal to one-twelfth the mass of one carbon-12 atom.
Ans: One atomic mass unit
114. ________________ are one of two or more distinct forms of an element.
Ans: Allotropes
115. When one of the hydrogen atoms in a molecule is replaced by a group of atoms, this group of
atoms is known as a ________________.
Ans: functional group
116. Briefly explain the relationship between hypothesis and experiment in the scientific method.
Ans: A hypothesis should be capable of leading to a prediction which is testable by experiment. If the experimental result differs from the prediction, the hypothesis should be
modified.
117. The table below describes four atoms.
Atom A
Number of protons
79
Number of neutrons
118
Number of electrons
79
Atom B
80
120
80
Atom C
80
118
80
Atom D
79
120
79
Which atoms represent the same element?
Ans: Atoms A and D represent the same element, Atoms B and C represent the same element.
118. In the early 1900s, Ernest Rutherford performed an experiment with gold foil, targets and alpha
particles to probe the structure of the atoms. He observed that most of these alpha particles
penetrated the foil undeflected. Realizing that atoms are electrically neutral (that is, they have
equal numbers of protons and electrons) and that the mass of a proton is significantly greater
than the mass of an electron, use Rutherford's data to propose a structural model of an atom.
Ans: (Answers will vary.) Atoms are mostly empty space. The mass is concentrated mostly at
the center of the atom.
119. Describe the contributions of Marie Curie.
Ans: (note that answers will vary) Marie Curie discovered two new elements, and is one of
three people to win two Nobel Prizes. She also suggested the term “radioactivity” to
describe the spontaneous emission of particles and/or radiation.
120. State the two important experimental results (and the names of the responsible scientists)
which enabled the mass of the electron to be determined.
Ans: Thomson measured m/e, the mass-to-charge ratio. Millikan measured e, the charge.
Thus, the mass m could be calculated.
121. Name the three important "laws" that were accounted for by Dalton's atomic theory.
Ans: Laws of conservation of mass; definite composition; multiple proportions
122. Dalton's atomic theory has required some modifications in the light of subsequent discoveries.
For any three appropriate postulates of Dalton's atomic theory: state the postulate in its original
form and in one sentence, describe why the postulate has needed modification.
Ans: Matter consists of atoms which are indivisible, cannot be created or destroyed. But, atoms are divisible, as the existence of subatomic particles shows.
Atoms of one element cannot be converted into atoms of another element. They can be
converted in various nuclear reactions, including radioactive decay. Atoms of an element
are identical in mass and other properties. Isotopes of an element differ in their masses
and other properties.
123. Describe the difference between an empirical formula and a molecular formula.
Ans: An empirical formula is the simplest chemical formula that has the smallest possible
whole number ratio of atoms in the formula and a molecular formula is the true formula
of a molecule which is a whole number multiple of its empirical formula.
124. Determine the average atomic mass of boron is the natural abundance of 10B weighing exactly
10.0129 amu is 19.9% and the natural abundance of 11B weighing exactly 11.0093 amu is 80.1%?
Show all your work.
Ans: (10.0129)(0.199) + (11.0093)(0.801) = 10.81 amu
125. Explain what is meant by an ionizable hydrogen atom.
Ans: It is one that separates from the molecule upon dissolving and becomes a hydrogen ion,
H +.
126. Describe what is meant by the term 'functional group' in organic chemistry.
Ans: A functional group is a group atoms that have replaced one of the hydrogen atoms in an
organic compound.
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