2: Atoms, Molecules, and Ions

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. C₆H₈O_{6​​​​​​​}

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%