Skip to main content
Chemistry LibreTexts

2: Atoms, Molecules, and Ions

  • Page ID
    214695
  • Isotopes

    Exercise \(\PageIndex{1}\)

    Ytterbium-169 (16970Yb is a radioactive isotope used in cerebrospinal fluid studies of the brain. Identify how many protons, neutrons and electrons are present

    a. 70 protons,99 neutrons & 70 electrons

    b. 99 protons,70 neutrons & 99 electrons

    c. 70 protons,99 neutrons & 99 electrons

    d. 169 protons,99 neutrons & 169 electrons

    Answer

    a. 70 protons,99 neutrons & 70 electrons

    Exercise \(\PageIndex{1}\)

    Which species has 48 electrons

    a. 11850Sn+2

    b. 6831Ga

    c. 11850Sn+4

    d. 11248Cd+2

    Answer

    a. 11850Sn+2

    Exercise \(\PageIndex{1}\)

    The average atomic weight of copper is 63.5 amu. Cu has 2 naturally occuring isotopes. One has a weight of 62.9amu and an abundance of 69.1%. What is the atomic weight of the other isotope?

    a. 63.2

    b. 63.8

    c. 64.1

    d. 64.8

    Answer

    d. 64.8

    Exercise \(\PageIndex{1}\)

    Silver has two isotopes, one of mass 106.9 amu and one of mass 108.9amu. What is the fractional abundance of the lighter isotope?

    a. .5160

    b. .4824

    c. .2763

    d. .6743

    Answer

    a. .5160

    Exercise \(\PageIndex{1}\)

    An unkown element is found to have 3 naturally occuring isotopes with the following masses and % abundance; 35.9675amu (.337%), 37.9627amu (0.063%) &  39.9624amu (99.600%). Which of the following is the unknown element?

    a. K

    b. Cl

    c. Ca

    d. Ar

    Answer

    d. Ar

    Exercise \(\PageIndex{1}\)

    Strontium-90 (90Sr) was released into the atmosphere during the Chernobyl nuclear accident. This isotope has:

    a. 90 protons, 38 neutrons & 90 electrons

    b. 52 protons, 38 neutrons & 52 electrons

    c. 38 protons, 52 neutrons & 38 electrons

    d. 38 protons, 90 neutrons & 52 electrons

    Answer

    c. 38 protons, 52 neutrons & 38 electrons

     

    Identifying Isotopic Compositions

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 48Ti

    a. 22, 22, 26

    b. 26, 22, 26

    c. 22, 26, 22

    d. 24, 24, 24

    Answer

    c. 22, 26, 22

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 116Sn+2

    a. 50, 66, 50

    b. 50, 66, 48

    c. 50, 66, 52

    d. 58, 58, 56

    Answer

    b. 50, 66, 48

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 31P-3

    a. 15, 16, 18

    b. 15, 16, 15

    c. 15, 16, 12

    d. 16, 15, 19

    Answer

    a. 15, 16, 18

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 68Ga

    a. 34, 34, 34

    b. 37, 31, 31

    c. 37, 31, 37

    d. 31, 37, 31

    Answer

    d. 31, 37, 31

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 112Cd+2

    a. 48, 64, 50

    b. 48, 64, 48

    c. 48, 64, 46

    d. 56, 56, 54

    Answer

    c. 48, 64, 46

    Exercise \(\PageIndex{1}\)

    There are ____ protons, ____ neutrons, and ____ electrons in 34S-2

    a. 16, 18, 14

    b. 16, 18, 18

    c. 16, 18, 16

    d. 17, 17, 19

    Answer

    b. 16, 18, 18

     

    Group Names

    Exercise \(\PageIndex{1}\)

    Rank the elements in the order of: Alkaline Earth Metal, Alkali Metal, Transition Metal, Halogen.

    a. Sodium, Magnesium, Copper, Oxygen

    b. Sodium, Magnesium, Copper, Chlorine

    c. Magnesium, Sodium, Copper, Oxygen

    d. Magnesium, Sodium, Copper, Chlorine

    Answer

    d. Magnesium, Sodium, Copper, Chlorine

    Exercise \(\PageIndex{1}\)

    Identify the Chalcogen.

    a. Phosphorus

    b. Tellurium

    c. Fluorine

    d. Magnesium

    Answer

    b. Tellurium

    Exercise \(\PageIndex{1}\)

    Rank the elements in the order of: Halogen, Alkali Metal, Noble Gas, Alkaline Earth Metal

    a. Bromine, Lithium, Argon, Potassium

    b. Iodine, Calcium, Krypton, Barium

    c. Chlorine, Rubidium, Radon, Beryllium

    d. Fluorine, Strontium, Xenon, Francium

    Answer

    c. Chlorine, Rubidium, Radon, Beryllium

    Exercise \(\PageIndex{1}\)

    Identify the Actinide

    a. Mercury

    b. Uranium

    c. Nitrogen

    d. Carbon

    Answer

    b. Uranium

    Exercise \(\PageIndex{1}\)

    Identify the Noble Gas

    a. Hydrogen

    b. Nitrogen

    c. Oxygen

    d. Neon

    Answer

    d. Neon

    Exercise \(\PageIndex{1}\)

    Rank the elements in the order of: Chalcogen, Actinide, Halogen, Alkali Metal.

    a. Iodine, Plutonium, Sulfur, Potassium

    b.  Bromine, Uranium, Oxygen, Calcium

    c. Tellurium, Plutonium, Fluorine, Sodium

    d. Selenium, Uranium, Chlorine, Radium

    Answer

    c. Tellurium, Plutonium, Fluorine, Sodium

     

    Metals, Nonmetals, and Metalloids

    Exercise \(\PageIndex{1}\)

    Lithium, Sulfur, and Barium are:

    a. All Metals

    b.  All nonmetals

    c. Metal, Nonmetal, Metal

    d. None of the above

    Answer

    c. Metal, Nonmetal, Metal

    Exercise \(\PageIndex{1}\)

    Hydrogen is a:

    a. Metal

    b. Nonmetal

    c. Both A and B

    d. None of the above

    Answer

    b. Nonmetal

    Exercise \(\PageIndex{1}\)

    Rank the elements in the order of: Metal, Nonmetal, Metalloid.

    a. Lithium, Neon, Calcium

    b. Hydrogen, Argon, Boron

    c. Radium, Sulfur, Aluminum

    d. Sodium, Nitrogen, Silicon

    Answer

    d. Sodium, Nitrogen, Silicon

    Exercise \(\PageIndex{1}\)

    Identify the Metalloid.

    a. Carbon

    b. Arsenic

    c. Gallium

    d. Chromium

    Answer

    b. Arsenic

    Exercise \(\PageIndex{1}\)

    Identify the Metal.

    a. Cobalt

    b. Antimony

    c. Both A and B

    d. None of the above

    Answer

    a. Cobalt

    Exercise \(\PageIndex{1}\)

    Rank the elements in the order of: Nonmetal, Metalloid, Metal.

    a. Boron, Carbon, Gold

    b. Selenium, Germanium, Tellurium

    c. Chlorine, Silicon, Silver

    d. Krypton, Aluminum, Nickel

    Answer

    c. Chlorine, Silicon, Silver

     

    Identifying Isotopic Composition

    Exercise \(\PageIndex{1}\)

    17P, 17N, 18e-

    a. 34Cl-

    b. 34F-

    c. 35Cl-

    d. none of the above 

    Answer

    a. 34Cl-

    Exercise \(\PageIndex{1}\)

    34P, 44N, 34e-

    a. 68Se

    b. 78Br

    c. 78Se

    d. 78Se

    Answer

    c. 78Se

    Exercise \(\PageIndex{1}\)

    82P, 128N, 78e-

    a. 160Hg+2

    b. 210Pb+4

    c. 160Pb+2

    d. 210Pb-4

    Answer

    b. 210Pb+4

    Exercise \(\PageIndex{1}\)

    7P, 6N, 10e-

    a. 17N-3

    b. 13N+4

    c. 17N-4

    d. 13N-3

    Answer

    d. 13N-3

    Exercise \(\PageIndex{1}\)

    92P, 143N, 92e-

    a. 225Ul+3

    b. 133U

    c. 225U

    d. 235U

    Answer

    d. 235U

    Exercise \(\PageIndex{1}\)

    27P, 32n, 25e-

    a. 59Co+2

    b. 59Co+3

    c. 52Co+2

    d. 52Co+3

    Answer

    a. 59Co+2

     

    Natural States of the Elements

    Exercise \(\PageIndex{1}\)

    Bromine is a ____.

    a. Gas

    b. Liquid

    c. Solid

    d. None of the above

    Answer

    b. Liquid

    Exercise \(\PageIndex{1}\)

    ____ and ____ are liquids.

    a. Iodine and Mercury

    b. Iodine and Bromine

    c. Bromine and Mercury

    d. None of the above

    Answer

    c. Bromine and Mercury

    Exercise \(\PageIndex{1}\)

    Chlorine is a ____.

    a. Gas

    b. Solid

    c. Liquid

    d. A and C

    Answer

    a. Gas

    Exercise \(\PageIndex{1}\)

    Other than Noble gasses, which elements gasses?

    a. Halogens

    b. Lighter diatomics

    c. A and B

    d. None of the above

    Answer

    b. Lighter diatomics

    Exercise \(\PageIndex{1}\)

    Name the lighter diatomics.

    a. Hydrogen, Nitrogen, and Oxygen

    b. Hydrogen, Nitrogen, Oxygen, and Chlorine

    c. Hydrogen, Nitrogen, Oxygen, Fluorine, and Chlorine

    d. None of the above

    Answer

    c. Hydrogen, Nitrogen, Oxygen, Fluorine, and Chlorine

    Exercise \(\PageIndex{1}\)

    ____, ____, ____, and ____ are solids.

    a. C, Ca, Cd, Cl

    b. C, Ca, Cd, Co

    c. C, Ca, Cd, Cu

    d. Both B and C

    Answer

    d. Both B and C

     

    Groups and Periods

    Exercise \(\PageIndex{1}\)

    Which element is in group V and Period 5?

    a. Se

    b. Sb

    c. Pb

    d. As

    Answer

    b. Sb

    Exercise \(\PageIndex{1}\)

    Which period is Siver in?

    a. 5A

    b. IB

    c. 11

    d. 5

    Answer

    d. 5

    Exercise \(\PageIndex{1}\)

    Which period is U in?

    a. 7

    b. 9

    c. none

    d. 2B

    Answer

    a. 7

    Exercise \(\PageIndex{1}\)

    Which element is in period IV and group VII?

    a. Barium

    b. Boron

    c. Cl

    d. Bromine

    Answer

    d. Bromine

    Exercise \(\PageIndex{1}\)

    Which period and group is He in?

    a. 1,VIII

    b. 1,7

    c. 2,7

    d. 1,2

    Answer

    a. 1,VIII

    Exercise \(\PageIndex{1}\)

    Which group and period is Tin in?

    a. VI, 4

    b. IV, 5

    c. IV, 4

    d. V, 4

    Answer

    b. IV, 5

     

    History of the Discovery of the Atom

    Exercise \(\PageIndex{1}\)

    Who is credited with determining the charge to mass ration of the electron?

    a. Millikan

    b. Dalton

    c. Rutherford

    d. Thomson

    Answer

    d. Thomson

    Exercise \(\PageIndex{1}\)

    Who is credited with determining the charge the electron?

    a. Millikan

    b. Thomas

    c. Rutherford

    d. Dalton

    Answer

    a. Millikan

    Exercise \(\PageIndex{1}\)

    Which type of radiation has the largest mass?

    a. gamma rays

    b. beta particles

    c. alpha particles

    Answer

    c. alpha particles

    Exercise \(\PageIndex{1}\)

    Who is credited with the nuclear model of the atom?

    a. Dalton

    b. Mulliken

    c. Rutherford

    d. Thomson

    Answer

    c. Rutherford

    Exercise \(\PageIndex{1}\)

    What type of radiation is not deflected by a magnetic field?

    a. gamma

    b. alpha

    c. beta

    Answer

    a. gamma

    Exercise \(\PageIndex{1}\)

    What type of radiation is actually an electron?

    a. gamma

    b. alpha

    c. beta

    Answer

    c. beta

     

    Empirical Formulas

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a sample which is 12.6% H & 87.4 % N?

    a. NH

    b. NH2

    c. NH3

    d. NH4

    Answer

    b. NH2

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a sample which is 17.7% H & 82.3 % N?

    a. NH

    b. NH2

    c. NH3

    d. NH4

    Answer

    c. NH3

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a sample which is 22.2% H & 77.8 % N?

    a. NH

    b. NH2

    c. NH3

    d. NH4

    Answer

    d. NH4

    Exercise \(\PageIndex{1}\)

    A sample is composed of the elements potassium, nitrogen and oxygen. What is its empirical formula if it is 38.7% potassium & 13.9% nitrogen?

    a. K2N2O3

    b. KNO2

    c. KNO3

    d. KN2O3

    Answer

    c. KNO3

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a compound that is 36.8% Nitrogen and 63.2% Oxygen?

    a. N2O5

    b. N2O3

    c. NO2

    d. NO3

    Answer

    b. N2O3

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a compound that is 48.2% C, 8.2% H & 43.2% O?

    a. C6H5O3

    b. CH3O

    c. C3H6O2

    d. C3H6O

    Answer

    c. C3H6O2

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a compound that contains 8.46 g Na, 11.81 g S and 8.87 g O?

    a. Na2SO3

    b. Na2S4

    c. Na2S2O3

    d. NaSO3

    Answer

    c. Na2S2O3

    Exercise \(\PageIndex{1}\)

    A material is deemed to be composed of the elements carbon, hydrogen and chlorine. Determine the empirical formula if a 9.66 g sample contains 4.74 g carbon and .264 g hydrogen.

    a. CHCl3

    b. CH3Cl

    c. CH2Cl2

    d. C3H2Cl

    Answer

    d. C3H2Cl

    Exercise \(\PageIndex{1}\)

    What is the empirical formula for a compound that is 29% Na, 40.5% S and 30.5% O by mass?

    a. Na4S4O6

    b. Na2S2O3

    c. NaSO4

    d. None of the above

    Answer

    b. Na2S2O3

    Exercise \(\PageIndex{1}\)

    What is the empirical formula of a compound that contains only 43.7 grams N and only 6.3 grams H?

    a. NH4

    b. NH3

    c. NH2

    d. None of the above

    Answer

    c. NH2

    Exercise \(\PageIndex{1}\)

    What is the empirical formula that is 43.3% sodium, 11.3% carbon, and 45.4% oxygen by mass?

    a. Na2CO2

    b. Na2CO3

    c. NaC2O3

    d. None of the above

    Answer

    b. Na2CO3

    Exercise \(\PageIndex{1}\)

    What is the empirical formula for a compound that contains only 13.0 grams lead, and only 2.0 grams oxygen?

    a. PbO2

    b. Pb3O2

    c. Pb2O3

    d. None of the above

    Answer

    a. PbO2

     

    Molecular Formula

    Exercise \(\PageIndex{1}\)

    Determine the molecular formula of CH2O. The molecular mass of the compound is 180.1g/mol.

    a. C4H6O4

    b. C6H12O6

    c. C12H6O12

    d. None of the above

    Answer

    b. C6H12O6

    Exercise \(\PageIndex{1}\)

    An organic compound is found to contain 42.9% carbon, 6.4% hydrogen by mass and the remainder of the compound is oxygen. Determine the molecular formula. The molecular mass of the compound is 504.4g/mol.

    a. C18H32O16

    b. C9H16O8

    c. C7H9O5

    d. None of the above

    Answer

    a. C18H32O16

    Exercise \(\PageIndex{1}\)

    A compound containing only carbon, hydrogen, and oxygen is found to contain 40.9% carbon and 54.5% oxygen by mass. The molecular mass of the compound is 176.13g/mol. Determine the molecular formula.

    a. C12H16O12

    b. C6H8O6

    c. C3H4O3

    d. None of the above

    Answer

    b. C6H8O6​​​​​​​

    Exercise \(\PageIndex{1}\)

    Determine the molecular formula of CH3O. The molecular mass of the compound is 62.07g/mol.

    a. CH3O

    b. C4H12O4

    c. C2H6O2

    d. None of the above

    Answer

    c. C2H6O2

    Exercise \(\PageIndex{1}\)

    A compound contains only carbon and hydrogen. It is 93.75% carbon by mass. Determine the molecular formula. The molecular mass of the compound is 128.2g/mol.

    a. C5H4

    b. C10H8

    c. C6H2

    d. None of the above

    Answer

    b. C10H8

     

    Nomenclature

    Exercise \(\PageIndex{1}\)

    What is the correct name for SF4?

    a. Sufur (IV) tetrafluoride

    b. Sulfur tetrafluoride

    c. Monosulfur tetrafluoride

    d. NOTA

    Answer

    b. Sulfur tetrafluoride

    Exercise \(\PageIndex{1}\)

    What is the correct name for Be3N2?

    a. Triberyllium dinitride

    b. Beryllium (VI) nitride

    c. Beryllium nitride

    d. NOTA

    Answer

    c. Beryllium nitride

    Exercise \(\PageIndex{1}\)

    What is the correct name for Hg(C2H3O2)2?

    a. Mercury (II) acetate

    b. Mercury acetate

    c. Mercury (II) diacetate

    d. NOTA

    Answer

    a. Mercury (II) acetat

    Exercise \(\PageIndex{1}\)

    What is the correct name for NH4CN?

    a. Ammonium cyanide

    b. Ammonia cyanide

    c. Ammonium nitrate

    d. NOTA

    Answer

    a. Ammonium cyanide

    Exercise \(\PageIndex{1}\)

    What is the correct name for HIO4?

    a. Hydroiodic acid

    b. Iodic acid

    c. Periodic acid

    d. NOTA

    Answer

    c. Periodic acid

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Aluminum chlorate.

    a. Al(ClO2)3

    b. Al(ClO3)3

    c. Al(ClO)3

    d. NOTA

    Answer

    b. Al(ClO3)3

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Magnesium hydroxide.

    a. MgO2

    b. MgO

    c. Mg(OH)2

    d. NOTA

    Answer

    c. Mg(OH)2

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Ammonium nitrate.

    a. NH4NO3

    b. NH4NO2

    c. NH3NO3

    d. NOTA

    Answer

    a. NH4NO3

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Potassium perchlorate.

    a. KClO3

    b. KClO4

    c. KClO2

    d. NOTA

    Answer

    b. KClO4

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Cobalt (III) chloride.

    a. Co3Cl3

    b. CoClO3

    c. CoCl3

    d. NOTA

    Answer

    c. CoCl3

    Exercise \(\PageIndex{1}\)

    What is the correct name for Hg2(C2H3O2)2?

    a. Mercury (III) acetate

    b. Mercury (I) acetate

    c. Mercury acetate

    d. NOTA

    Answer

    b. Mercury (I) acetate

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Dichlorine heptoxide.

    a. Cl2O6

    b. ClO7

    c. Cl2O7

    d. NOTA

    Answer

    c. Cl2O7

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Cesium bicarbonate.

    a. Cs(HCO3)2

    b. CsHCO3

    c. Cs(CO3)2

    d. NOTA

    Answer

    b. CsHCO3

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Calcium hydride.

    a. CaH2

    b. CaH

    c. CaOH

    d. NOTA

    Answer

    a. CaH2

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Chromium (III) sulfide.

    a. Cr3S2

    b. Cr2S3

    c. CrS

    d. NOTA

    Answer

    b. Cr2S3

    Exercise \(\PageIndex{1}\)

    Give the correct formula for Copper (II) nitrate.

    a. Cu(NO3)2

    b. CuNO3

    c. Cu2NO3

    d. NOTA

    Answer

    a. Cu(NO3)2

    Exercise \(\PageIndex{1}\)

    What is the correct name for Ca3P2?

    a. Calcium phosphide

    b. Calcium phosphate

    c. Calcium (II) phosphate

    d. NOTA

    Answer

    a. Calcium phosphide

    Exercise \(\PageIndex{1}\)

    What is the correct name for Ag3PO4?

    a. Silver (III) phosphite

    b. Silver (III) phosphate

    c. Silver phosphate

    d. NOTA

    Answer

    c. Silver phosphate

    Exercise \(\PageIndex{1}\)

    What is the correct name for SnBr4?

    a. Tin bromide

    b. Tin (IV) bromide

    c. Tin (IV) bromate

    d. NOTA

    Answer

    b. Tin (IV) bromide

    Exercise \(\PageIndex{1}\)

    What is the correct name for MgClO?

    a. Magnesium chlorate

    b. Magnesium chlorite

    c. Magnesium hypochlorite

    d. NOTA

    Answer

    c. Magnesium hypochlorite

    Exercise \(\PageIndex{1}\)

    What is the correct name for HClO3?

    a. Chloric acid

    b. Hydrochloric acid

    c. Hydrogen chlorate

    d. NOTA

    Answer

    a. Chloric acid

    Exercise \(\PageIndex{1}\)

    What is the correct name for KO2?

    a. Potassium superoxide

    b. Potassium dioxide

    c. Potassium peroxide

    d. NOTA

    Answer

    a. Potassium superoxide

    Exercise \(\PageIndex{1}\)

    What is the correct name for Na2O?

    a. Sodium peroxide

    b. Sodium oxide

    c. Sodium superoxide

    d. NOTA

    Answer

    b. Sodium oxide

    Exercise \(\PageIndex{1}\)

    What is the correct name for Na2O2?

    a. Sodium superoxide

    b. Sodium oxide

    c. Sodium peroxide

    d. NOTA

    Answer

    c. Sodium peroxide

     

    Mass Percents of Atoms

    Exercise \(\PageIndex{1}\)

    Calculate the mass percent composition of calcium in calcium chloride.

    a. 50.0%

    b. 36.1%

    c. 33.0%

    d. None of the above

    Answer

    b. 36.1%

    Exercise \(\PageIndex{1}\)

    What is the mass percent composition of sodium in sodium chloride?

    a. 39.3%

    b. 51.0%

    c. 46.5%

    d. None of the above

    Answer

    a. 39.3%

    Exercise \(\PageIndex{1}\)

    Given the organic molecule, C6H12O6, calculate the mass percent oxygen in the molecule.

    a. 6.7%

    b. 40.0%

    c. 53.3%

    d. None of the above

    Answer

    c. 53.3%

    Exercise \(\PageIndex{1}\)

    What is the mass percent of carbon in methane, CH4?

    a. 74.9%

    b. 20.0%

    c. 25.1%

    d. None of the above

    Answer

    a. 74.9%

    Exercise \(\PageIndex{1}\)

    Calculate the mass percent sulfur in Cu2S

    a. 50.0%

    b. 20.1%

    c. 33.3%

    d. None of the above

    Answer

    b. 20.1%

     

    • Was this article helpful?