Chemistry Ch. 5 Practice Test

How many types of electrical charge exist? A. 1 B. 2 C. 3 D. 4

B; Difficulty: easy; Reference:

What is the relative electrical charge of a neutron? A. -1 B. +1 C. +2 D. 0

D; Difficulty: easy; Reference:

An atom of silver-108 contains 47 protons, 47 electrons, and 61 neutrons.

True; Difficulty: easy; Reference:

A substance has 13 protons, 14 neutrons, and 13 electrons. Which isotope is it? A. Al-13 B. Al-14 C. Al-27 D. Al-40

C; Difficulty: easy; Reference:

An isotope of sodium has the atomic number 11 and the mass number 23. An atom of this isotope contains A. 12 electrons B. 12 protons C. 12 neutrons D. 23 electrons

C; Difficulty: easy; Reference:

Atom A has 5 protons and 6 neutrons; atom B has 6 protons and 5 neutrons. These atoms are A. isotopes of the same element. B. isomers of the same element. C. atoms of different elements. D. identical in physical properties.

C; Difficulty: easy; Reference:

Let Z represent atomic number, A represent mass number, and N represent the number of neutrons in an atom. Which of the following is correct? A. N = A + Z B. Z = A + N C. N = A - Z D. A = N - Z

C; Difficulty: easy; Reference:

One isotope of oxygen has the atomic number 8 and the mass number 18. An atom of this isotope contains A. 8 neutrons B. 10 electrons C. 8 protons D. 18 electrons

C; Difficulty: easy; Reference:

The Law of Multiple Proportions states that A. atoms of one element may combine in different ratios to form more than one compound. B. atoms of one element may combine in different ratios to form the same compound. C. atoms of two or more elements may combine in different ratios to form more than one compound. D. atoms of two or more elements may combine in different ratios to produce the same compound.

C; Difficulty: easy; Reference:

The average mass of one atom of carbon is 2.00 10 -23 g. How many carbon atoms are present in a 40.0g sample of carbon? A. 7.96 10 -22 B. 4.98 10 -25 C. 2.00 10 24 D. 2.06 10 4

C; Difficulty: easy; Reference:

The concept that most of the atom's mass is concentrated in a small nucleus surrounded by electrons was the contribution of A. Dalton B. Thomson C. Rutherford D. Chadwick

C; Difficulty: easy; Reference:

The electrical charge of an atom is A. positive. B. negative. C. the atom has no charge, it is neutral.

C; Difficulty: easy; Reference:

The element with atomic number 27 is A. Carbon B. Copper C. Cobalt D. Calcium

C; Difficulty: easy; Reference:

The element with atomic number 53 is A. Iron B. Iridium C. Iodine D. Indium

C; Difficulty: easy; Reference:

The mass of a hydrogen atom is 1.673 x 10^-24 g. How many hydrogen atoms are present in a 1.00g sample of hydrogen? A. 1.00 atom B. 1.67 x 10^-24 atoms C. 5.98 x 10^23 atoms D. 1.67 x 10^24 atoms

C; Difficulty: easy; Reference:

The mass of an atom is primarily determined by the mass of its A. protons. B. neutrons. C. both, choices A and B. D. neither choices A nor B.

C; Difficulty: easy; Reference:

What is the mass number of an atom that contains 30 protons, 30 electrons, and 35 neutrons? A. 5 B. 30 C. 65 D. 95

C; Difficulty: easy; Reference:

What is the relative mass of a neutron? A. 1/1837 amu B. ½ amu C. 1 amu D. 2 amu

C; Difficulty: easy; Reference:

What is the relative mass of a proton? A. 1/1837 amu B. ½ amu C. 1 amu D. 2 amu

C; Difficulty: easy; Reference:

Which is not part of Dalton's atomic model? A. Elements are composed of minute, indivisible particles called atoms. B. Atoms of the same element are alike in mass. C. Atoms of the same element can be different in size. D. Chemical compounds are composed of two or more atoms of different elements.

C; Difficulty: easy; Reference:

Which isotope contains the same number of protons, neutrons, and electrons? A. H-1 B. Na-23 C. C-12 D. Al-27

C; Difficulty: easy; Reference:

Which subatomic particle contributes least to the mass of an atom? A. Proton B. Neutron C. Electron

C; Difficulty: easy; Reference:

Which subatomic particle contributes least to the mass of the nucleus? A. Proton B. Neutron C. Electron

C; Difficulty: easy; Reference:

Which subatomic particle is not found in the nucleus of the atom? A. Proton B. Neutron C. Electron

C; Difficulty: easy; Reference:

An atom of zinc has a mass of 65.39 amu. One of its isotopes,, has an 18.75% abundance. Since 1 amu = 1.6606 x 10-24 g, how many of atoms of this zinc isotope would be present in a 1.00 g sample of zinc? 9.209 x 1021 atoms 4.911 x 1022 atoms 1.727 x 1021 atoms 4.762 x 1021 atoms

C; Difficulty: hard; Reference:

The mass number of an ion that consists of 38 protons, 50 neutrons and 36 electrons is 38. 87.62. 88. 74.

C; Difficulty: medium; Reference:

Which of the following pairs of hypothetical atoms are isotopes? 50Cr 52Cr 53Cr 54Cr

C; Difficulty: medium; Reference:

Define in simple terms the concept of natural abundance for the isotopes of any element and how it determines the average atomic masses of the elements.

Imagine taking a random sample of 100 atoms of any element in the periodic table. The natural abundance of each isotope corresponds to how many atoms of each isotope we would have among those 100 atoms from our original sample. Because not all of the atoms from a single element are equal in everything (i.e., they may have different number of neutrons), the contribution to the average atomic mass of an element needs to be calculated from not only the masses of each of its isotopes but also their relative contributions to the total mass based on their natural abundances. Difficulty: medium; Reference:

In 1911 Ernest Rutherford performed an experiment known as the "Gold Foil Experiment." He fired a stream of positively charged alpha particles at a sheet of gold foil which was approximately 1000 atoms thick. Alpha particles have a mass of 4 amu and a charge of +2. Almost all of the alpha particles passed straight through 1000 atoms of gold. A few particles were deflected or even bounced back from the foil. Alpha particles are more than 7000 times more massive than electrons. What can you conclude regarding the structure of the atom from these observations?

The fact that most of the particles passed straight through 1000 atoms and struck nothing means that the vast majority of the volume of an atom is empty space. The alpha particle has a mass of 4 amu and a charge of +2. They would be deflected by relatively massive positively charged regions. Since only very few particles were deflected, this region would have to be very small. Since the majority of the mass of the atom is located in this very small volume, the volume would be extremely dense. As a result of these interpretations Rutherford envisioned an atom with these properties: (1) The great majority of the volume is empty space. (2) There is a very small, very dense, positively charged region within the atom. We now call this region the nucleus.; Difficulty: easy; Reference:

Rubidium occurs naturally as two isotopes: with a mass of 84.9117 amu and with a mass of 86.9092 amu. Given that the atomic mass of rubidium is 85.47 amu, what are the natural abundances of the two isotopes?

= 72.05%; = 27.95%; Difficulty: hard; Reference:

The nucleus of an Ar-40 atom has a radius of 4.1 x 10 -15 m. An atom of Ar-40 has a radius of 9.4 x 10 -11 m. The volume of a sphere can be calculated using the formula, . Assume that both the nucleus and the atom are spherical in shape. A. Calculate the volume of an Ar-40 nucleus. B. Calculate the volume of an Ar-40 atom. C. How many times larger is the volume of an Ar-40 atom than that of its nucleus?

A. 2.9 10 -43 m 3; B. 3.5 10 -30 m 3; C. 1.2 10 13 times; Difficulty: hard; Reference:

The nucleus of a C-12 atom has a radius of 2.7 x 10 -15 m. An atom of C-12 has a radius of 7.7 x 10 -11 m. The volume of a sphere can be calculated using the formula, . Assume that both the nucleus and the atom are spherical in shape. A. Calculate the volume of a C-12 nucleus. B. Calculate the volume of a C-12 atom. C. How many times larger is the volume of a C-12 atom than that of its nucleus?

A. 8.2 10 -44 m 3; B. 1.9 10 -30 m 3 ; C. 2.3 10 13 times; Difficulty: hard; Reference:

These questions refer to an atom of the isotope 65Cu. A. What is the atomic number of this element? B. What is the mass number of this isotope? C. How many protons, neutrons, and electrons are in this atom? D. What is the nuclear charge of this atom? E. What is the overall charge of this atom?

A. Atomic number = 29; B. Mass number = 65; C. In this atom there are 29 protons, 36 neutrons, and 29 electrons.; D. The nuclear charge of this atom is +29. The overall charge of this atom is zero.; Difficulty: easy; Reference:

An atom of gallium has a mass of 69.72 amu. On of its isotopes, , has a 39.89% abundance. Since 1 amu = 1.6606 x 10-24 g, how many atoms of this gallium isotope would be present in a 1.00 mg sample of gallium? 3.445 x 1018 atoms 8.637 x 1018 atoms 2.165 x 1019 atoms 9.501 x 1018 atoms

A; Difficulty: easy; Reference:

Atoms of isotopes of an element contain the same number of A. protons. B. neutrons. C. alpha particles.

A; Difficulty: easy; Reference:

How many electrons are in a neutral atom of Ar-40? A. 18 B. 22 C. 40 D. 58

A; Difficulty: easy; Reference:

How many protons are in a neutral atom of Ar-40? A. 18 B. 22 C. 40 D. 58

A; Difficulty: easy; Reference:

In isotopic notation mass number is represented by the superscript A. A B. N C. P D. Z

A; Difficulty: easy; Reference:

The Law of Definite proportions pertains to A. compounds composed of elements. B. mixtures composed of compounds. C. compounds composed of mixtures. D. mixtures composed of elements.

A; Difficulty: easy; Reference:

The electrical charge of a nucleus is A. positive. B. negative. C. the nucleus has no charge, it is neutral.

A; Difficulty: easy; Reference:

The mass of a copper atom is 1.045 x 10 -22 g. How many copper atoms are present in a 94.5g sample of copper? A. 9.04 x 10 23 B. 1.045 x 10 -22 C. 1870 D. 94.5

A; Difficulty: easy; Reference:

The number of electrons in an atom of iron-56 is A. 26 B. 30 C. 53 D. 3

A; Difficulty: easy; Reference:

The number of protons in an atom of sodium-23 is A. 11 B. 12 C. 16 D. 23

A; Difficulty: easy; Reference:

What charge does a cation possess? A. Positive B. Negative C. Neutral

A; Difficulty: easy; Reference:

What is the atomic number of an atom that contains 9 protons, 9 electrons, and 10 neutrons? A. 9 B. 10 C. 18 D. 19

A; Difficulty: easy; Reference:

What is the atomic number of magnesium? A. 12 B. 24 C. 25 D. 55

A; Difficulty: easy; Reference:

What is the atomic number of sodium? A. 11 B. 16 C. 23 D. 32

A; Difficulty: easy; Reference:

What is the relative electrical charge of an electron? A. -1 B. +1 C. -2 D. 0

A; Difficulty: easy; Reference:

What is the relative mass of an electron? A. 1/1837 amu B. ½ amu C. 1 amu D. 2 amu

A; Difficulty: easy; Reference:

Which contains the fewest neutrons? A. H-2 B. H-3 C. He-4 D. He-5

A; Difficulty: easy; Reference:

How are the different isotopes of an element alike; how are they different?

All isotopes of an element always have the same number of protons or atomic number. The difference between various isotopes of an element is that they have different numbers of neutrons and different mass numbers.; Difficulty: easy; Reference:

What is meant by the terms atom and ion? How are they alike and how are they different? Give examples.

An atom is the smallest neutral particle of an element that can enter into a chemical reaction. Atoms are composed of protons, neutrons and electrons. In atoms the number of protons always equals the number of electrons. Atoms are always electrically neutral. An ion is a positively or negatively charged particle, consisting of one or more atoms, which has either gained or lost electrons. If it gains electrons it acquires a negative charge and if it loses electrons it acquires a positive charge; Difficulty: medium; Reference:

Which particle contributes most to the electrical charge of the nucleus? A. Proton B. Neutron C. Electron

A; Difficulty: easy; Reference:

Based on the following information, calculate the mass of one atom of . mass of an electron = 9.110 x 10-28 g mass of a proton = 1.673 x 10-24 g mass of a neutron = 1.675 x 10-24 g 1.440 x 10-22 g 87.62 g 2.077 x 10-22 g 1.455 x 10-22 g

A; Difficulty: hard; Reference:

Sulfur occurs naturally as four isotopes: 32S with a mass of 31.9721 amu, 33S with a mass of 32.9715 amu, 34S 33.9679 amu, and 36S with a mass of 35.9671 amu. Based on the information that is given on the periodic table, which isotope is the most abundant? 32S 33S 34S 36S

A; Difficulty: hard; Reference:

An ion that consists of 33 protons, 42 neutrons, and 36 electrons has gained three electrons. lost three electrons. gained six electrons. lost nine electrons.

A; Difficulty: medium; Reference:

Explain why the atomic masses of elements are not whole numbers.

Atomic masses are not whole numbers because they are weighted averages of the masses of the naturally occurring isotopes of an element. While an average could be a whole number, usually it is not; Difficulty: medium; Reference:

Naturally occurring neon exists as three isotopes. 90.51% is Ne-20 with a mass of 19.99 amu, 0.27% is Ne-21 with a mass of 20.99 amu, and 9.22% is Ne-22 with a mass of 21.99 amu. What is the atomic mass of neon? A. 10.00 amu B. 20.18 amu C. 20.99 amu D. 62.97 amu

B; Difficulty: medium; Reference:

Naturally occurring silicon exists as three isotopes. 92.23% is Si-28 with a mass of 27.977 amu, 4.67% is Si- 29 with a mass of 28.977 amu, and 3.10% is Si-30 with a mass of 29.974 amu. What is the atomic mass of silicon? A. 14.00 amu B. 28.09 amu C. 28.98 amu D. 86.93 amu

B; Difficulty: medium; Reference:

The name of the isotope containing one proton and two neutrons is A. protium. B. deuterium. C. tritium. D. helium.

C; Difficulty: easy; Reference:

The nucleus of an atom usually contains A. protons. B. neutrons. C. both, choices A and B. D. neither, choices A nor B.

C; Difficulty: easy; Reference:

What is the mass number of an atom that contains 23 protons, 23 electrons, and 28 neutrons? A. 5 B. 28 C. 51 D. 74

C; Difficulty: easy; Reference:

Isotopes of an element always have the same A. mass number. B. number of neutrons. C. number of subatomic particles. D. atomic number.

D; Difficulty: easy; Reference:

Models of the atom were proposed by Rutherford, Dalton, and Thomson. Which choice places them in the correct chronological order of their appearance? A. Rutherford, Dalton, Thomson B. Thomson, Rutherford, Dalton C. Dalton, Rutherford, Thomson D. Dalton, Thomson, Rutherford

D; Difficulty: easy; Reference:

Neutral atoms of a specific element may have different A. atomic numbers. B. number of protons. C. number of electrons. D. mass numbers.

D; Difficulty: easy; Reference:

One isotope of carbon has the atomic number 6 and the mass number 14. An atom of this isotope contains A. 8 protons B. 14 neutrons C. 6 neutrons D. 6 electrons

D; Difficulty: easy; Reference:

Which contains the largest number of neutrons? A. C-12 B. P-31 C. Br-80 D. Sr-90

D; Difficulty: easy; Reference:

Cations are electrically negative and anions are electrically positive.

False; Difficulty: easy; Reference:

Dalton's atomic model states that all atoms are composed of protons, neutrons, and electrons.

False; Difficulty: easy; Reference:

The mass number of an atom is the sum of its protons plus electrons.

False; Difficulty: easy; Reference:

The neutron has a charge of negative one.

False; Difficulty: easy; Reference:

Every atom is electrically neutral.

True; Difficulty: easy; Reference:

One atomic mass unit is 1/12 the mass of an atom of carbon-12.

True; Difficulty: easy; Reference:

Rutherford's gold foil experiment proved that the volume of the atom is mostly empty space.

True; Difficulty: easy; Reference:

The three isotopes of hydrogen are protium, deuterium, and tritium.

True; Difficulty: easy; Reference:

A substance has 15 protons, 16 neutrons, and 15 electrons. Which isotope is it? A. P-30 B. P-31 C. S-30 D. S-31

B; Difficulty: easy; Reference:

As the distance between two particles with charges that attract one another increases, the force of attraction will A. increase. B. decrease. C. remain the same.

B; Difficulty: easy; Reference:

As the distance between two particles with charges that repel each other increases, the force of repulsion will A. increase B. decrease C. remain the same

B; Difficulty: easy; Reference:

Atoms of isotopes of an element contain different numbers of A. protons. B. neutrons. C. electrons.

B; Difficulty: easy; Reference:

Different isotopes of an element are atoms of that element which have A. the same atomic number and the same mass number. B. the same atomic number and different mass number. C. different atomic number and the same mass number. D. different atomic number and different mass number.

B; Difficulty: easy; Reference:

Particles with which electric charges will attract one another? A. Positive and positive B. Positive and negative C. Negative and negative D. Both, choices A and B

B; Difficulty: easy; Reference:

The atomic mass of an element is A. the mass of the most abundant isotope of that element. B. the weighted average of the masses of the naturally occurring isotopes of that element. C. the arithmetic average of the masses of the isotopes of that element. D. the ratio of the mass of one atom of an isotope of that element to the mass of hydrogen.

B; Difficulty: easy; Reference:

The combined number of protons and neutrons in an atom is known as its A. atomic number. B. mass number. C. atomic mass. D. molecular mass.

B; Difficulty: easy; Reference:

The element with atomic number 53 always contains A. 53 neutrons B. 53 protons C. 26 neutrons and 27 protons D. 26 protons and 27 neutrons

B; Difficulty: easy; Reference:

The number of electrons in an atom of phosphorous-31 is A. 9 B. 15 C. 16 D. 22

B; Difficulty: easy; Reference:

The number of protons in an atom is known as its A. atomic Mass. B. atomic number. C. mass number. D. molecular mass.

B; Difficulty: easy; Reference:

The number of protons in an atom of boron-11 is A. 4 B. 5 C. 6 D. 7

B; Difficulty: easy; Reference:

What charge does an anion possess? A. Positive B. Negative C. Neutral

B; Difficulty: easy; Reference:

What is the atomic number of an atom that contains 40 protons, 40 electrons, and 51 neutrons? A. 11 B. 40 C. 51 D. 91

B; Difficulty: easy; Reference:

What is the number of neutrons in a neutral atom of Ar-40? A. 18 B. 22 C. 40 D. 58

B; Difficulty: easy; Reference:

What is the relative electrical charge of a proton? A. -1 B. +1 C. -2 D. 0

B; Difficulty: easy; Reference:

Which experiment led to the notion that the atom contains an extremely small, positively charged nucleus? A. Millikan's oil drop experiment B. Rutherford's gold foil experiment C. Thomson's cathode ray experiment D. Dalton's atomic experiment

B; Difficulty: easy; Reference:

Which of the following is not supported by Dalton's Atomic Theory? atoms isotopes compounds elements

B; Difficulty: easy; Reference:

Which subatomic particle(s) was not part of the Thomson model of the atom? A. Proton B. Neutron C. Electron D. Both, choices A and B

B; Difficulty: easy; Reference:

Chromium occurs naturally as four isotopes: 50Cr with a mass of 49.9460 amu, 52Cr with a mass of 51.9405 amu, 53Cr with a mass of 52.9407 amu, and 54Cr with a mass of 53.9389 amu. Based on the information that is given on the periodic table, which isotope is the most abundant? 50Cr 52Cr 53Cr 54Cr

B; Difficulty: hard; Reference:

Ions can be formed from atoms by losing or gaining electrons. Select the alternative that states the correct number of protons, neutrons, and electrons in . 13 protons, 14 neutrons, and 16 electrons 13 protons, 14 neutrons, and 10 electrons 10 protons, 17 neutrons, 13 electrons 13 protons, 27 neutrons, 10 electrons

B; Difficulty: hard; Reference:

Ions can be formed from atoms by losing or gaining electrons. Select the alternative that states the correct number of protons, neutrons, and electrons in . 17 protons, 18 neutrons, 16 electrons 17 protons, 18 neutrons, 18 electrons 18 protons, 17 neutrons, 19 electrons 17 protons, 36 neutrons, 17 electrons

B; Difficulty: hard; Reference:

Ions can be formed from atoms by losing or gaining electrons. Select the alternative that states the correct number of protons, neutrons, and electrons in . 29 protons, 34 neutrons, 31 electrons 29 protons, 34 neutrons, 27 electrons 27 protons, 29 neutrons, 29 electrons 29 protons, 63 neutrons, 29 electrons

B; Difficulty: hard; Reference:

Ca-40, K-39, and Sc-41 all have the same A. atomic mass. B. atomic number. C. number of electrons. D. number of neutrons.

D; Difficulty: easy; Reference:

In isotopic notation atomic number is represented by the subscript A. A B. N C. P D. Z

D; Difficulty: easy; Reference:

Particles with which electrical charges will repel one another? A. Positive and positive B. Positive and negative C. Negative and negative D. Both choices A and C

D; Difficulty: easy; Reference:

The Law of Definite Composition states that A. a compound always contains one element physically combined in variable proportions by mass. B. a compound always contains one element chemically combined in a definite proportion by mass. C. a compound always contains two or more elements physically combined in variable proportions by mass. D. a compound always contains two or more elements chemically combined in a definite proportion by mass.

D; Difficulty: easy; Reference:

The average mass of an atom of sulfur is 5.33 10 -23 g. How many sulfur atoms are present in a 100.0g sample of sulfur? A. 5.33 10 -21 B. 1.88 10 -21 C. 5.33 10 24 D. 1.88 10 24

D; Difficulty: easy; Reference:

The number of protons and neutrons in an atom are added to find the atom's A. atomic number. B. ionic charge. C. number of electrons. D. mass number.

D; Difficulty: easy; Reference:

Which isotope has the same number of protons, neutrons, and electrons? A. Cl-35 B. Cl-37 C. P-31 D. S-32

D; Difficulty: easy; Reference:

Which pair of formulas illustrates the Law of Multiple Proportions? A. CH3Cl and CH3OH B. H2O and HOH C. CuCl2 and CuBr D. H2O and H2O2

D; Difficulty: easy; Reference:

Based on the following information, calculate the mass of one atom of . mass of an electron = 9.110 x 10-28 g mass of a proton = 1.673 x 10-24 g mass of a neutron = 1.675 x 10-24 g 58.69 g 1.474 x 10-22 g 9.746 x 10-23 g 1.005 x 10-22 g

D; Difficulty: hard; Reference:

An ion that consists of 24 protons, 30 neutrons, and 22 electrons has gained six electrons. lost eight electrons. gained two electrons. lost two electrons.

D; Difficulty: medium; Reference:

Compare and contrast the mass, electrical charge, and location of the three major subatomic particles.

The proton has a mass of one amu, a charge of positive one, and is located in the nucleus of the atom. The neutron has a mass of one amu, no electrical charge, and is located in the nucleus of the atom. The electron has a mass of 1/1836 amu, a charge of negative one, and is located outside the nucleus of the atom.; Difficulty: easy; Reference:

Explain how Rutheford's gold foil experiment changed the model of the atom proposed by Thomson.

Thomson's model of the atom (or "plum-pudding model"), portrayed all subatomic particles scattered over the volume of the atom. Rutherford's gold foil experiment showed instead that the protons were concentrated in a very small, dense region (the nucleus) and that most of the volume occupied by an atom is actually empty space. Difficulty: easy; Reference:

The atomic number of an atom is equal to its number of protons.

True; Difficulty: easy; Reference:

The majority of the mass of an atom is contained in a very small, very dense, positively charged region.

True; Difficulty: easy; Reference:

The majority of the volume of an atom is empty space.

True; Difficulty: easy; Reference: