• Home
  • Textbooks
  • Chemistry
  • Atoms, Molecules, and Ions

Chemistry

Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson

Chapter 2

Atoms, Molecules, and Ions - all with Video Answers

Educators

Chapter Questions

01:30

Problem 1

In the following drawing, the green spheres represent atoms of a certain element. The purple spheres represent atoms of another element. If the spheres of different elements touch, they are part of a single unit of a compound. The following chemical change represented by these spheres may violate one of the ideas of Dalton’s atomic theory. Which one?

Rikhil Makwana
Rikhil Makwana
Numerade Educator
00:44

Problem 2

Which postulate of Dalton’s theory is consistent with the following observation concerning the weights of reactants and products? When 100 grams of solid calcium carbonate is heated, 44 grams of carbon dioxide and 56 grams of calcium oxide are produced.

William Mills
William Mills
Numerade Educator
01:16

Problem 3

Identify the postulate of Dalton’s theory that is violated by the following observations: 59.95% of one sample of titanium dioxide is titanium; 60.10% of a different sample of titanium dioxide is titanium

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:14

Problem 4

Samples of compound X, Y, and Z are analyzed, with results shown here.

Do these data provide example(s) of the law of definite proportions, the law of multiple proportions, neither, or both? What do these data tell you about compounds X, Y, and Z?

William Mills
William Mills
Numerade Educator
01:54

Problem 5

he existence of isotopes violates one of the original ideas of Dalton’s atomic theory. Which one?

Rikhil Makwana
Rikhil Makwana
Numerade Educator
00:44

Problem 6

How are electrons and protons similar? How are they different?

William Mills
William Mills
Numerade Educator
01:08

Problem 7

How are protons and neutrons similar? How are they different?

Rikhil Makwana
Rikhil Makwana
Numerade Educator
07:11

Problem 8

Predict and test the behavior of ? particles fired at a “plum pudding” model atom.

(a) Predict the paths taken by ? particles that are fired at atoms with a Thomson’s plum pudding model structure. Explain why you expect the ? particles to take these paths.
(b) If ? particles of higher energy than those in (a) are fired at plum pudding atoms, predict how their paths will differ from the lower-energy ? particle paths. Explain your reasoning.
(c) Now test your predictions from (a) and (b). Open the Rutherford Scattering simulation
(http://openstaxcollege.org/l/16PhetScatter) and select the “Plum Pudding Atom” tab. Set “Alpha Particles Energy” to “min,” and select “show traces.” Click on the gun to start firing ? particles. Does this match your prediction from (a)? If not, explain why the actual path would be that shown in the simulation. Hit the pause button, or “Reset All.” Set “Alpha Particles Energy” to “max,” and start firing ? particles. Does this match your prediction from (b)? If not, explain the effect of increased energy on the actual paths as shown in the simulation.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
09:51

Problem 9

Predict and test the behavior of ? particles fired at a Rutherford atom model.

(a) Predict the paths taken by ? particles that are fired at atoms with a Rutherford atom model structure. Explain why you expect the ? particles to take these paths.
(b) If ? particles of higher energy than those in (a) are fired at Rutherford atoms, predict how their paths will differ from the lower-energy ? particle paths. Explain your reasoning.
(c) Predict how the paths taken by the ? particles will differ if they are fired at Rutherford atoms of elements other than gold. What factor do you expect to cause this difference in paths, and why?
(d) Now test your predictions from (a), (b), and (c). Open the Rutherford Scattering simulation
(http://openstaxcollege.org/l/16PhetScatter) and select the “Rutherford Atom” tab. Due to the scale of the simulation, it is best to start with a small nucleus, so select “20” for both protons and neutrons, “min” for energy, show traces, and then start firing ? particles. Does this match your prediction from (a)? If not, explain why the actual path would be that shown in the simulation. Pause or reset, set energy to “max,” and start firing ? particles. Does this match your prediction from (b)? If not, explain the effect of increased energy on the actual path as shown in the simulation. Pause or reset, select “40” for both protons and neutrons, “min” for energy, show traces, and fire away. Does this match your prediction from (c)? If not, explain why the actual path would be that shown in the simulation. Repeat this with larger numbers of protons and neutrons. What generalization can you make regarding the type of atom and effect on the path of ? particles? Be clear and specific.

Ronald Prasad
Ronald Prasad
Numerade Educator
01:09

Problem 10

In what way are isotopes of a given element always different? In what way(s) are they always the same?

William Mills
William Mills
Numerade Educator
03:09

Problem 11

Write the symbol for each of the following ions:

(a) the ion with a 1+ charge, atomic number 55, and mass number 133
(b) the ion with 54 electrons, 53 protons, and 74 neutrons
(c) the ion with atomic number 15, mass number 31, and a 3? charge
(d) the ion with 24 electrons, 30 neutrons, and a 3+ charge

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:30

Problem 12

Write the symbol for each of the following ions:

(a) the ion with a 3+ charge, 28 electrons, and a mass number of 71
(b) the ion with 36 electrons, 35 protons, and 45 neutrons
(c) the ion with 86 electrons, 142 neutrons, and a 4+ charge
(d) the ion with a 2+ charge, atomic number 38, and mass number 87

William Mills
William Mills
Numerade Educator
04:48

Problem 13

Open the Build an Atom simulation (http://openstaxcollege.org/l/16PhetAtomBld) and click on the Atom icon.

(a) Pick any one of the first 10 elements that you would like to build and state its symbol.
(b) Drag protons, neutrons, and electrons onto the atom template to make an atom of your element.
State the numbers of protons, neutrons, and electrons in your atom, as well as the net charge and mass number.
(c) Click on “Net Charge” and “Mass Number,” check your answers to (b), and correct, if needed.
(d) Predict whether your atom will be stable or unstable. State your reasoning.
(e) Check the “Stable/Unstable” box. Was your answer to (d) correct? If not, first predict what you can do to make a stable atom of your element, and then do it and see if it works. Explain your reasoning.

Ronald Prasad
Ronald Prasad
Numerade Educator
02:27

Problem 14

Open the Build an Atom simulation (http://openstaxcollege.org/l/16PhetAtomBld)

(a) Drag protons, neutrons, and electrons onto the atom template to make a neutral atom of Oxygen-16 and give the isotope symbol for this atom.
(b) Now add two more electrons to make an ion and give the symbol for the ion you have created.

Ronald Prasad
Ronald Prasad
Numerade Educator
01:16

Problem 15

Open the Build an Atom simulation (http://openstaxcollege.org/l/16PhetAtomBld)

(a) Drag protons, neutrons, and electrons onto the atom template to make a neutral atom of Lithium-6 and give the isotope symbol for this atom.
(b) Now remove one electron to make an ion and give the symbol for the ion you have created

Rikhil Makwana
Rikhil Makwana
Numerade Educator
03:23

Problem 16

Determine the number of protons, neutrons, and electrons in the following isotopes that are used in medical diagnoses:

(a) atomic number 9, mass number 18, charge of 1?
(b) atomic number 43, mass number 99, charge of 7+
(c) atomic number 53, atomic mass number 131, charge of 1?
(d) atomic number 81, atomic mass number 201, charge of 1+
(e) Name the elements in parts (a), (b), (c), and (d).

William Mills
William Mills
Numerade Educator
02:34

Problem 17

The following are properties of isotopes of two elements that are essential in our diet. Determine the number of protons, neutrons and electrons in each and name them.

(a) atomic number 26, mass number 58, charge of 2+
(b) atomic number 53, mass number 127, charge of 1?

Rikhil Makwana
Rikhil Makwana
Numerade Educator
View

Problem 18

Give the number of protons, electrons, and neutrons in neutral atoms of each of the following isotopes:

(a) $\stackrel{10}{5} B$
(b) $\stackrel{199}{80} Hg$
(c) $\stackrel{63}{29} Cu$
(d) $\stackrel{13}{6} C$
(e) $\stackrel{77}{34} Se$

Miguel Perez
Miguel Perez
Numerade Educator
02:12

Problem 19

Give the number of protons, electrons, and neutrons in neutral atoms of each of the following isotopes:

(a) $\stackrel{7}{3} Li$
(b) $\stackrel{125}{52} Te$
(c) $\stackrel{109}{47} Ag$
(d) $\stackrel{15}{7} N$
(e) $\stackrel{31}{15} P$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
05:46

Problem 20

Click on the site (http://openstaxcollege.org/l/16PhetAtomMass) and select the “Mix Isotopes” tab,
hide the “Percent Composition” and “Average Atomic Mass” boxes, and then select the element boron.

(a) Write the symbols of the isotopes of boron that are shown as naturally occurring in significant amounts.
(b) Predict the relative amounts (percentages) of these boron isotopes found in nature. Explain the reasoning behind your choice.
(c) Add isotopes to the black box to make a mixture that matches your prediction in (b). You may drag isotopes from their bins or click on “More” and then move the sliders to the appropriate amounts.
(d) Reveal the “Percent Composition” and “Average Atomic Mass” boxes. How well does your mixture match with your prediction? If necessary, adjust the isotope amounts to match your prediction.
(e) Select “Nature’s” mix of isotopes and compare it to your prediction. How well does your prediction compare with the naturally occurring mixture? Explain. If necessary, adjust your amounts to make them match “Nature’s” amounts as closely as possible.

Ronald Prasad
Ronald Prasad
Numerade Educator
07:02

Problem 21

Repeat Exercise 2.20 using an element that has three naturally occurring isotopes.

Ronald Prasad
Ronald Prasad
Numerade Educator
01:40

Problem 22

An element has the following natural abundances and isotopic masses: 90.92% abundance with 19.99 amu, 0.26% abundance with 20.99 amu, and 8.82% abundance with 21.99 amu. Calculate the average atomic mass of this element

William Mills
William Mills
Numerade Educator
02:21

Problem 23

Average atomic masses listed by IUPAC are based on a study of experimental results. Bromine has two
isotopes $^{79} Br$ and $^{81} Br,$ whose masses (78.9183 and 80.9163 amu) and abundances (50.69% and 49.31%) were determined in earlier experiments. Calculate the average atomic mass of bromine based on these experiments.

Rikhil Makwana
Rikhil Makwana
Numerade Educator
04:24

Problem 24

Variations in average atomic mass may be observed for elements obtained from different sources. Lithium provides an example of this. The isotopic composition of lithium from naturally occurring minerals is 7.5% $^{6} Li$ and 92.5% $^{7} Li,$ which have masses of 6.01512 amu and 7.01600 amu, respectively. A commercial source of lithium, recycled from a military source, was 3.75% $^{6} Li$ (and the rest $^{7} Li$). Calculate the average atomic mass values for each of these two sources.

Pam Owens
Pam Owens
Numerade Educator
05:17

Problem 25

The average atomic masses of some elements may vary, depending upon the sources of their ores. Naturally occurring boron consists of two isotopes with accurately known masses $\left(^{10} B, 10.0129 amu \text { and }^{11} B, 11.0931 amu\right)$ The actual atomic mass of boron can vary from 10.807 to 10.819, depending on whether the mineral source is from Turkey or the United States. Calculate the percent abundances leading to the two values of the average atomic masses of boron from these two countries.

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:08

Problem 26

The $^{18} O :^{16} O$ abundance ratio in some meteorites is greater than that used to calculate the average atomic mass of oxygen on earth. Is the average mass of an oxygen atom in these meteorites greater than, less than, or equal to that of a terrestrial oxygen atom?

William Mills
William Mills
Numerade Educator
00:50

Problem 27

Explain why the symbol for an atom of the element oxygen and the formula for a molecule of oxygen differ.

Rikhil Makwana
Rikhil Makwana
Numerade Educator
00:32

Problem 28

Explain why the symbol for the element sulfur and the formula for a molecule of sulfur differ.

William Mills
William Mills
Numerade Educator
02:46

Problem 29

Write the molecular and empirical formulas of the following compounds:

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:08

Problem 30

Write the molecular and empirical formulas of the following compounds:

William Mills
William Mills
Numerade Educator
01:37

Problem 31

Determine the empirical formulas for the following compounds:

(a) caffeine, $C_{8} H_{10} N_{4} O_{2}$
(b) fructose, $C_{12} H_{22} O_{11}$
(c) hydrogen peroxide, $H_{2} O_{2}$
(d) glucose, $C_{6} H_{12} O_{6}$
(e) ascorbic acid (vitamin $C ), C_{6} {H}_{8} O_{6}$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:51

Problem 32

Determine the empirical formulas for the following compounds:

(a) acetic acid, $C_{2} H_{4} O_{2}$
(b) citric acid, $C_{6} H_{8} \mathrm{O}_{7}$
(c) hydrazine, $\mathrm{N}_{2} \mathrm{H}_{4}$
(d) nicotine, $C_{10} H_{14} N_{2}$
(e) butane, $C_{4} H_{10}$

William Mills
William Mills
Numerade Educator
00:46

Problem 33

Write the empirical formulas for the following compounds:

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:29

Problem 34

Open the Build a Molecule simulation (http://openstaxcollege.org/l/16molbuilding) and select the
“Larger Molecules” tab. Select an appropriate atoms “Kit” to build a molecule with two carbon and six hydrogen atoms. Drag atoms into the space above the “Kit” to make a molecule. A name will appear when you have made an actual molecule that exists (even if it is not the one you want). You can use the scissors tool to separate atoms if you would like to change the connections. Click on “3D” to see the molecule, and look at both the space-filling and ball and-stick possibilities.

(a) Draw the structural formula of this molecule and state its name.
(b) Can you arrange these atoms in any way to make a different compound?

Ronald Prasad
Ronald Prasad
Numerade Educator
02:19

Problem 35

Use the Build a Molecule simulation (http://openstaxcollege.org/l/16molbuilding) to repeat Exercise 2.34, but build a molecule with two carbons, six hydrogen, and one oxygen.

(a) Draw the structural formula of this molecule and state its name.
(b) Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state its name.
(c) How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the type of relationship between these molecules, not their names).

Ronald Prasad
Ronald Prasad
Numerade Educator
03:09

Problem 36

Use the Build a Molecule simulation (http://openstaxcollege.org/l/16molbuilding) to repeat Exercise 2.34, but build a molecule with three carbons, seven hydrogen, and one chlorine.

(a) Draw the structural formula of this molecule and state its name.
(b) Can you arrange these atoms to make a different molecule? If so, draw its structural formula and state its name.
(c) How are the molecules drawn in (a) and (b) the same? How do they differ? What are they called (the type of relationship between these molecules, not their names)?

Ronald Prasad
Ronald Prasad
Numerade Educator
03:09

Problem 37

Using the periodic table, classify each of the following elements as a metal or a nonmetal, and then further classify each as a main-group (representative) element, transition metal, or inner transition metal:

(a) uranium
(b) bromine
(c) strontium
(d) neon
(e) gold
(f) americium
(g) rhodium
(h) sulfur
(i) carbon
(j) potassium

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:58

Problem 38

Using the periodic table, classify each of the following elements as a metal or a nonmetal, and then further classify each as a main-group (representative) element, transition metal, or inner transition metal:

(a) cobalt
(b) europium
(c) iodine
(d) indium
(e) lithium
(f) oxygen
(g) cadmium
(h) terbium
(i) rhenium

William Mills
William Mills
Numerade Educator
00:48

Problem 39

Using the periodic table, identify the lightest member of each of the following groups:

(a) noble gases
(b) alkaline earth metals
(c) alkali metals
(d) chalcogens

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:22

Problem 40

Using the periodic table, identify the heaviest member of each of the following groups:

(a) alkali metals
(b) chalcogens
(c) noble gases
(d) alkaline earth metals

William Mills
William Mills
Numerade Educator
01:25

Problem 41

Use the periodic table to give the name and symbol for each of the following elements:

(a) the noble gas in the same period as germanium
(b) the alkaline earth metal in the same period as selenium
(c) the halogen in the same period as lithium
(d) the chalcogen in the same period as cadmium

Rikhil Makwana
Rikhil Makwana
Numerade Educator
03:32

Problem 42

Use the periodic table to give the name and symbol for each of the following elements:

(a) the halogen in the same period as the alkali metal with 11 protons
(b) the alkaline earth metal in the same period with the neutral noble gas with 18 electrons
(c) the noble gas in the same row as an isotope with 30 neutrons and 25 protons
(d) the noble gas in the same period as gold

William Mills
William Mills
Numerade Educator
01:56

Problem 43

Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number for each.

(a) the alkali metal with 11 protons and a mass number of 23
(b) the noble gas element with 75 neutrons in its nucleus and 54 electrons in the neutral atom
(c) the isotope with 33 protons and 40 neutrons in its nucleus
(d) the alkaline earth metal with 88 electrons and 138 neutrons

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:21

Problem 44

Write a symbol for each of the following neutral isotopes. Include the atomic number and mass number for each.

(a) the chalcogen with a mass number of 125
(b) the halogen whose longest-lived isotope is radioactive
(c) the noble gas, used in lighting, with 10 electrons and 10 neutrons
(d) the lightest alkali metal with three neutrons

William Mills
William Mills
Numerade Educator
01:29

Problem 45

Using the periodic table, predict whether the following chlorides are ionic or covalent: $KCl, NCl_{3}, ICl, MgCl_{2},PCl_{5},$ and $CCl_{4}$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:11

Problem 46

Using the periodic table, predict whether the following chlorides are ionic or covalent: $SiCl_{4}, PCl_{3},CaCl_{2},CsCl, CuCl_{2},$ and $CrCl_{3}.$

William Mills
William Mills
Numerade Educator
01:30

Problem 47

For each of the following compounds, state whether it is ionic or covalent. If it is ionic, write the symbols for the ions involved:

(a) $NF_{3}$
(b) $BaO$
(c) $\left(NH_{4}\right)_{2} CO_{3}$
(d) $\operatorname{Sr}\left(H_{2} PO_{4}\right)_{2}$
(e) $IBr$
(f) $Na_{2} O$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:58

Problem 48

For each of the following compounds, state whether it is ionic or covalent, and if it is ionic, write the symbols for the ions involved:

(a) $\mathrm{KClO}_{4}$
(b) $\mathrm{Mg}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}$
(c) $\mathrm{H}_{2} \mathrm{S}$
(d) $\mathrm{Ag}_{2} \mathrm{S}$
(e) $\mathrm{N}_{2} \mathrm{Cl}_{4}$
(f) $\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}$

William Mills
William Mills
Numerade Educator
01:32

Problem 49

For each of the following pairs of ions, write the formula of the compound they will form:

(a) $Ca^{2+}, S^{2-}$
(b) $NH_{4}^{+}, SO_{4}^{2-}$
(c) $Al^{3+}, Br^{-}$
(d) $Na^{+}, HPO_{4}^{2-}$
(e) $Mg^{2+}, PO_{4}^{3-}$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:48

Problem 50

For each of the following pairs of ions, write the formula of the compound they will form:

(a) $K^{+}, O^{2-}$
(b) $NH_{4}^{+}, PO_{4}^{3-}$
(c) $Al^{3+}, O^{2-}$
(d) $Na^{+}, CO_{3}^{2-}$
(e) $Ba^{2+}, PO_{4}^{3-}$

William Mills
William Mills
Numerade Educator
01:27

Problem 51

Name the following compounds:

(a) $CsCl$
(b) $BaO$
(c) $K_{2} S$
(d) $BeCl_{2}$
(e) $HBr$
(f) $AlF_{3}$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
01:51

Problem 52

Name the following compounds:

(a) $NaF$
(b) $Rb_{2} O$
(c) $BCl_{3}$
(d) $H_{2} Se$
(e) $P_{4} O_{6}$
(f) $ICl_{3}$

William Mills
William Mills
Numerade Educator
01:05

Problem 53

Write the formulas of the following compounds:

(a) rubidium bromide
(b) magnesium selenide
(c) sodium oxide
(d) calcium chloride
(e) hydrogen fluoride
(f) gallium phosphide
(g) aluminum bromide
(h) ammonium sulfate

Rikhil Makwana
Rikhil Makwana
Numerade Educator
04:17

Problem 54

Write the formulas of the following compounds:

(a) lithium carbonate
(b) sodium perchlorate
(c) barium hydroxide
(d) ammonium carbonate
(e) sulfuric acid
(f) calcium acetate
(g) magnesium phosphate
(h) sodium sulfite

William Mills
William Mills
Numerade Educator
00:52

Problem 55

Write the formulas of the following compounds:

(a) chlorine dioxide
(b) dinitrogen tetraoxide
(c) potassium phosphide
(d) silver(I) sulfide
(e) aluminum nitride
(f) silicon dioxide

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:47

Problem 56

Write the formulas of the following compounds:

(a) barium chloride
(b) magnesium nitride
(c) sulfur dioxide
(d) nitrogen trichloride
(e) dinitrogen trioxide
(f) tin(IV) chloride

William Mills
William Mills
Numerade Educator
01:38

Problem 57

Each of the following compounds contains a metal that can exhibit more than one ionic charge. Name these compounds:

(a) $Cr_{2} O_{3}$
(b) $FeCl_{2}$
(c) $CrO_{3}$
(d) $TiCl_{4}$
(e) $CoO$
(f) $MoS_{2}$

Rikhil Makwana
Rikhil Makwana
Numerade Educator
03:41

Problem 58

Each of the following compounds contains a metal that can exhibit more than one ionic charge. Name these compounds:

(a) $NiCO_{3}$
(b) $MoO_{3}$
(c) $Co\left(\mathrm{NO}_{3}\right)_{2}$
(d) $\mathrm{V}_{2} \mathrm{O}_{5}$
(e) $\mathrm{MnO}_{2}$
(f) $Fe_{2} O_{3}$

William Mills
William Mills
Numerade Educator
00:56

Problem 59

The following ionic compounds are found in common household products. Write the formulas for each
compound:

(a) potassium phosphate
(b) copper(II) sulfate
(c) calcium chloride
(d) titanium(IV) oxide
(e) ammonium nitrate
(f) sodium bisulfate (the common name for sodium hydrogen sulfate)

Rikhil Makwana
Rikhil Makwana
Numerade Educator
02:14

Problem 60

The following ionic compounds are found in common household products. Name each of the compounds:

(a) $\mathrm{Ca}\left(\mathrm{H}_{2} \mathrm{PO}_{4}\right)_{2}$
(b) $\mathrm{FeSO}_{4}$
(c) $\mathrm{CaCO}_{3}$
(d) $MgO$
(e) $\mathrm{NaNO}_{2}$
(f) $\mathrm{KI}$

William Mills
William Mills
Numerade Educator
01:23

Problem 61

What are the IUPAC names of the following compounds?

(a) manganese dioxide
(b) mercurous chloride $\left(Hg_{2} Cl_{2}\right)$
(c) ferric nitrate $\left[\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}\right]$
(d) titanium tetrachloride
(e) cupric bromide $\left(\mathrm{CuBr}_{2}\right)$

Rikhil Makwana
Rikhil Makwana
Numerade Educator