Chemistry

Raymond Chang, Kenneth A. Goldsby

Chapter 2

Atoms, Molecules, and Ions - all with Video Answers

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Chapter Questions

Problem 1

Define the following terms: (a) $\alpha$ particle, (b) $\beta$ particle, (c) $\gamma$ ray, (d) X ray.

Aishu Sanchula

Aishu Sanchula

Numerade Educator

Problem 2

Name the types of radiation known to be emitted by radioactive elements.

Wan Deng

Numerade Educator

Problem 3

Compare the properties of the following: $\alpha$ particles, cathode rays, protons, neutrons, electrons.

Aishu Sanchula

Numerade Educator

Problem 4

What is meant by the term "fundamental particle"?

Wan Deng

Numerade Educator

Problem 5

Describe the contributions of the following scientists to our knowledge of atomic structure: J. J. Thomson,
R. A. Millikan, Ernest Rutherford, James Chadwick.

Aishu Sanchula

Numerade Educator

Problem 6

Describe the experimental basis for believing that the nucleus occupies a very small fraction of the volume of the atom.

Wan Deng

Numerade Educator

Problem 7

The diameter of a helium atom is about $1 \times 10^{2} \mathrm{pm}$ Suppose that we could line up helium atoms side by side in contact with one another. Approximately how many atoms would it take to make the distance from end to end $1 \mathrm{cm} ?$

Aishu Sanchula

Numerade Educator

Problem 8

Roughly speaking, the radius of an atom is about 10,000 times greater than that of its nucleus. If an atom were magnified so that the radius of its nucleus became $2.0 \mathrm{cm},$ about the size of a marble, what would be the radius of the atom in miles? $(1 \mathrm{mi}=1609 \mathrm{m}$.)

Wan Deng

Numerade Educator

Problem 9

Use the helium- 4 isotope to define atomic number and mass number. Why does a knowledge of atomic number enable us to deduce the number of electrons present in an atom?

Aishu Sanchula

Numerade Educator

Problem 10

Why do all atoms of an element have the same atomic number, although they may have different mass numbers?

Wan Deng

Numerade Educator

Problem 11

What do we call atoms of the same elements with different mass numbers?

Aishu Sanchula

Numerade Educator

Problem 12

Explain the meaning of each term in the symbol $_{Z}^{A} X$.

Wan Deng

Numerade Educator

Problem 13

What is the mass number of an iron atom that has 28 neutrons?

Aishu Sanchula

Numerade Educator

Problem 14

Calculate the number of neutrons in $^{239} \mathrm{Pu}$.

Wan Deng

Numerade Educator

Problem 15

For each of the following species, determine the number of protons and the number of neutrons in the nucleus:
$_{2}^{3} \mathrm{He},_{2}^{4} \mathrm{He},_{12}^{24} \mathrm{Mg},_{12}^{25} \mathrm{Mg},_{22}^{48} \mathrm{Ti},_{35}^{79} \mathrm{Br},_{78}^{195} \mathrm{Pt}$

Aishu Sanchula

Numerade Educator

Problem 16

Indicate the number of protons, neutrons, and electrons in each of the following species:
$$_{7}^{15} \mathrm{N},_{16}^{33} \mathrm{S},_{29}^{63} \mathrm{Cu},_{38}^{84} \mathrm{Sr},_{56}^{130} \mathrm{Ba},_{74}^{186} \mathrm{W},_{80}^{202} \mathrm{Hg}$$

Wan Deng

Numerade Educator

Problem 17

Write the appropriate symbol for each of the following isotopes: (a) $Z=11, A=23 ;$ (b) $Z=28$ $A=64$

Aishu Sanchula

Numerade Educator

Problem 18

Write the appropriate symbol for each of the following isotopes: (a) $Z=74, A=186 ;$ (b) $Z=80$ $A=201$

Wan Deng

Numerade Educator

Problem 19

What is the periodic table, and what is its significance in the study of chemistry?

Aishu Sanchula

Numerade Educator

Problem 20

State two differences between a metal and a nonmetal.

Wan Deng

Numerade Educator

Problem 21

Write the names and symbols for four elements in each of the following categories: (a) nonmetal,
(b) metal, (c) metalloid.

Aishu Sanchula

Numerade Educator

Problem 22

Define, with two examples, the following terms:
(a) alkali metals, (b) alkaline earth metals, (c) halogens, (d) noble gases.

Wan Deng

Numerade Educator

Problem 23

Elements whose names end with -ium are usually metals; sodium is one example. Identify a nonmetal whose name also ends with -ium.

Aishu Sanchula

Numerade Educator

Problem 24

Describe the changes in properties (from metals to nonmetals or from nonmetals to metals) as we move
(a) down a periodic group and (b) across the periodic table from left to right.

Wan Deng

Numerade Educator

Problem 25

Consult a handbook of chemical and physical data (ask your instructor where you can locate a copy of the handbook) to find (a) two metals less dense than water, (b) two metals more dense than mercury, (c) the densest known solid metallic element, (d) the densest known solid nonmetallic element.

Charles Thomas

Numerade Educator

Problem 26

Group the following elements in pairs that you would expect to show similar chemical properties:
$\mathrm{K}, \mathrm{F}, \mathrm{P}, \mathrm{Na}, \mathrm{Cl},$ and $\mathrm{N}$

Wan Deng

Numerade Educator

Problem 27

What is the difference between an atom and a molecule?

Aishu Sanchula

Numerade Educator

Problem 28

What are allotropes? Give an example. How are allotropes different from isotopes?

Wan Deng

Numerade Educator

Problem 29

Describe the two commonly used molecular models.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 30

Give an example of each of the following: (a) a monatomic cation, (b) a monatomic anion, (c) a polyatomic cation, (d) a polyatomic anion.

Wan Deng

Numerade Educator

Problem 31

Which of the following diagrams represent diatomic molecules, polyatomic molecules, molecules that are not compounds, molecules that are compounds, or an elemental form of the substance?

Susan Hallstrom

Susan Hallstrom

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Problem 32

Which of the following diagrams represent diatomic molecules, polyatomic molecules, molecules that are not compounds, molecules that are compounds, or an elemental form of the substance?

Wan Deng

Numerade Educator

Problem 33

Identify the following as elements or compounds:
$\mathrm{NH}_{3}, \mathrm{N}_{2}, \mathrm{S}_{8}, \mathrm{NO}, \mathrm{CO}, \mathrm{CO}_{2}, \mathrm{H}_{2}, \mathrm{SO}_{2}$

Aishu Sanchula

Numerade Educator

Problem 34

Give two examples of each of the following: (a) a diatomic molecule containing atoms of the same element, (b) a diatomic molecule containing atoms of different elements, (c) a polyatomic molecule containing atoms of the same element, (d) a polyatomic molecule containing atoms of different elements.

Wan Deng

Numerade Educator

Problem 35

Give the number of protons and electrons in each of the following common ions: $\mathrm{Na}^{+}, \mathrm{Ca}^{2+}, \mathrm{Al}^{3+}, \mathrm{Fe}^{2+}$
$\bar{I}^{-}, F^{-}, S^{2-}, O^{2-},$ and $N^{3-}$

Aishu Sanchula

Numerade Educator

Problem 36

Give the number of protons and electrons in each of the following common ions: $\mathrm{K}^{+}, \mathrm{Mg}^{2+}, \mathrm{Fe}^{3+}, \mathrm{Br}^{-}$
$\mathrm{Mn}^{2+}, \mathrm{C}^{4-}, \mathrm{Cu}^{2+}$

Wan Deng

Numerade Educator

Problem 37

What does a chemical formula represent? What is the ratio of the atoms in the following molecular formulas? (a) $\mathrm{NO},$ (b) $\mathrm{NCl}_{3},$ (c) $\mathrm{N}_{2} \mathrm{O}_{4},$ (d) $\mathrm{P}_{4} \mathrm{O}_{6}$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 38

Define molecular formula and empirical formula. What are the similaritics and differences between the empirical formula and molecular formula of a compound?

Wan Deng

Numerade Educator

Problem 39

Give an example of a case in which two molecules have different molecular formulas but the same empirical formula.

Aishu Sanchula

Numerade Educator

Problem 40

What does $P_{4}$ signify? How does it differ from $4 P ?$

Wan Deng

Numerade Educator

Problem 41

What is an ionic compound? How is electrical neutrality maintained in an ionic compound?

Aishu Sanchula

Numerade Educator

Problem 42

Explain why the chemical formulas of ionic compounds are usually the same as their empirical formulas.

Wan Deng

Numerade Educator

Problem 43

Write the formulas for the following ionic compounds: (a) sodium oxide, (b) iron sulfide (containing the $\mathrm{Fe}^{2+}$ ion), (c) cobalt sulfate (containing the $\mathrm{Co}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions), and (d) barium fluoride. (Hint: See Figure $2.11 .)$

Aishu Sanchula

Numerade Educator

Problem 44

Write the formulas for the following ionic compounds: (a) copper bromide (containing the $\mathrm{Cu}^{+}$ ion), (b) manganese oxide (containing the $M n^{3+}$ ion), (c) mercury iodide (containing the $\mathrm{Hg}_{2}^{2+}$ ion), and (d) magnesium phosphate (containing the $\mathrm{PO}_{4}^{3-}$ ion). (Hint: See Figure 2.11.)

Wan Deng

Numerade Educator

Problem 45

What are the empirical formulas of the following compounds? (a) $\mathrm{C}_{2} \mathrm{N}_{2},$ (b) $\mathrm{C}_{6} \mathrm{H}_{6},$ (c) $\mathrm{C}_{9} \mathrm{H}_{20},$ (d) $\mathrm{P}_{4} \mathrm{O}_{10}$
(e) $\mathrm{B}_{2} \mathrm{H}_{6}$

Aishu Sanchula

Numerade Educator

Problem 46

What are the empirical formulas of the following compounds? (a) $\mathrm{Al}_{2} \mathrm{Br}_{6},$ (b) $\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{4},$ (c) $\mathrm{N}_{2} \mathrm{O}_{5}$ (d) $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$

Wan Deng

Numerade Educator

Problem 47

Write the molecular formula of glycine, an amino acid present in proteins. The color codes are: black (carbon), blue (nitrogen), red (oxygen), and gray (hydrogen).

Aishu Sanchula

Numerade Educator

Problem 48

Write the molecular formula of ethanol. The color codes are: black (carbon), red (oxygen), and gray (hydrogen).

Wan Deng

Numerade Educator

Problem 49

Which of the following compounds are likely to be ionic? Which are likely to be molecular? SiCl_, LiF, $\mathrm{BaCl}_{2}, \mathrm{B}_{2} \mathrm{H}_{6}, \mathrm{KCl}, \mathrm{C}_{2} \mathrm{H}_{4}$

Aishu Sanchula

Numerade Educator

Problem 50

Which of the following compounds are likely to be ionic? Which are likely to be molecular? $\mathrm{CH}_{4}, \mathrm{NaBr}$ $\mathrm{BaF}_{2}, \mathrm{CCl}_{4}, \mathrm{ICl}, \mathrm{CsCl}, \mathrm{NF}_{3}$

Wan Deng

Numerade Educator

Problem 51

What is the difference between inorganic compounds and organic compounds?

Charles Thomas

Numerade Educator

Problem 52

What are the four major categories of inorganic compounds?

Wan Deng

Numerade Educator

Problem 53

Give an example each for a binary compound and a ternary compound.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 54

What is the Stock system? What are its advantages over the older system of naming cations?

Wan Deng

Numerade Educator

Problem 55

Explain why the formula HCI can represent two different chemical systems.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 56

Define the following terms: acids, bases, oxoacids, oxoanions, and hydrates.

Wan Deng

Numerade Educator

Problem 57

Name these compounds: (a) $\mathrm{Na}_{2} \mathrm{CrO}_{4},$ (b) $\mathrm{K}_{2} \mathrm{HPO}_{4}$
(c) $\mathrm{HBr}$ (gas), (d) $\mathrm{HBr}$ (in water), (e) $\mathrm{Li}_{2} \mathrm{CO}_{3}$ (f) $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7},(\mathrm{g}) \mathrm{NH}_{4} \mathrm{NO}_{2},(\mathrm{h}) \mathrm{PF}_{3},(\mathrm{i}) \mathrm{PF}_{5,}(\mathrm{j}) \mathrm{P}_{4} \mathrm{O}_{6}$
(k) $\mathrm{CdI}_{2},(1) \operatorname{SrSO}_{4},(\mathrm{m}) \mathrm{Al}(\mathrm{OH})_{3},(\mathrm{n}) \mathrm{Na}_{2} \mathrm{CO}_{3} \cdot 10 \mathrm{H}_{2} \mathrm{O}$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 58

Name these compounds: (a) $\mathrm{KClO},$ (b) $\mathrm{Ag}_{2} \mathrm{CO}_{3}$
(c) $\mathrm{FeCl}_{2},$ (d) $\mathrm{KMnO}_{4}$, (e) $\mathrm{CsClO}_{3}$, (f) $\mathrm{HIO},$ (g) $\mathrm{FeO}$ (h) $\mathrm{Fe}_{2} \mathrm{O}_{3},$ (i) $\mathrm{TiCl}_{4},(\mathrm{j}) \mathrm{NaH},(\mathrm{k}) \mathrm{Li}_{3} \mathrm{N},(\mathrm{l}) \mathrm{Na}_{2} \mathrm{O}$
$(\mathrm{m}) \mathrm{Na}_{2} \mathrm{O}_{2},(\mathrm{n}) \mathrm{FeCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O}$

Wan Deng

Numerade Educator

Problem 59

Write the formulas for the following compounds:
(a) rubidium nitrite, (b) potassium sulfide, (c) sodium hydrogen sulfide, (d) magnesium phosphate, (e) calcium hydrogen phosphate, (f) potassium dihydrogen phosphate, (g) iodine heptafluoride, (h) ammonium sulfate, (i) silver perchlorate, (j) boron trichloride.

Aishu Sanchula

Numerade Educator

Problem 60

Write the formulas for the following compounds:
(a) copper(I) cyanide, (b) strontium chlorite, (c) perbromic acid, (d) hydroiodic acid, (e) disodium ammonium phosphate, (f) lead(II) carbonate, (g) tin(II) fluoride,
(h) tetraphosphorus decasulfide, (i) mercury(II) oxide,
(j) mercury(I) iodide, (k) selenium hexafluoride.

Wan Deng

Numerade Educator

Problem 61

Sulfur (S) and fluorine (F) form several different compounds. One of them, $\mathrm{SF}_{6}$, contains $3.55 \mathrm{g}$ of $\mathrm{F}$ for every gram of S. Use the law of multiple proportions to determine $n,$ which represents the number of F atoms in $\mathrm{SF}_{n},$ given that it contains $2.37 \mathrm{g}$ of $\mathrm{F}$ for every gram of S.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 62

Name the following compounds.

Lottie Adams

Numerade Educator

Problem 63

Pair the following species that contain the same number of electrons: $\mathrm{Ar}, \mathrm{Sn}^{4+}, \mathrm{F}^{-}, \mathrm{Fe}^{3+}, \mathrm{P}^{3-}, \mathrm{V}$
$\mathrm{Ag}^{+}, \mathrm{N}^{3-}$

Aishu Sanchula

Numerade Educator

Problem 64

Write the correct symbols for the atoms that contain:
(a) 25 protons, 25 electrons, and 27 neutrons; (b) 10 protons, 10 electrons, and 12 neutrons; (c) 47 protons, 47 electrons, and 60 neutrons; (d) 53 protons,
53 electrons, and 74 neutrons; (e) 94 protons,
94 electrons, and 145 neutrons.

Wan Deng

Numerade Educator

Problem 65

A sample of a uranium compound is found to be losing mass gradually. Explain what is happening to the sample.

Charles Thomas

Numerade Educator

Problem 66

In which one of the following pairs do the two species resemble each other most closely in chemical properties? Explain. (a) $_{1}^{1} \mathbf{H}$ and $_{1}^{1} \mathbf{H}^{+},$ (b) $^{14} \mathbf{N}$ and $_{7}^{14} \mathrm{N}^{3-},(\mathrm{c})_{6}^{12} \mathrm{C}$ and $_{6}^{13} \mathrm{C}$

Wan Deng

Numerade Educator

Problem 67

One isotope of a metallic element has mass number 65 and 35 neutrons in the nucleus. The cation derived from the isotope has 28 electrons. Write the symbol for this cation.

Aishu Sanchula

Numerade Educator

Problem 68

One isotope of a nonmetallic element has mass number 127 and 74 neutrons in the nucleus. The anion derived from the isotope has 54 electrons. Write the symbol for this anion.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 69

Determine the molecular and empirical formulas of the compounds shown here. (Black spheres are carbon and gray spheres are hydrogen.)

Aishu Sanchula

Numerade Educator

Problem 70

What is wrong with or ambiguous about the phrase "four molecules of NaCl"?

Wan Deng

Numerade Educator

Problem 71

The following phosphorus sulfides are known: $\mathrm{P}_{4} \mathrm{S}_{3}$ $\mathrm{P}_{4} \mathrm{S}_{7},$ and $\mathrm{P}_{4} \mathrm{S}_{10}$. Do these compounds obey the law of multiple proportions?

Charles Thomas

Numerade Educator

Problem 72

Which of the following are elements, which are molecules but not compounds, which are compounds but not molecules, and which are both compounds and molecules? (a) $\mathrm{SO}_{2},$ (b) $\mathrm{S}_{8}$
(c) $\mathrm{Cs},$ (d) $\mathrm{N}_{2} \mathrm{O}_{5},$ (e) $\mathrm{O},$ (f) $\mathrm{O}_{2},(\mathrm{g}) \mathrm{O}_{3},$ (h) $\mathrm{CH}_{4}$
(i) $\mathrm{KBr},$ (j) $\mathrm{S},$ (k) $\mathrm{P}_{4},$ (1) $\mathrm{LiF}$

Wan Deng

Numerade Educator

Problem 73

The following table gives numbers of electrons, protons, and neutrons in atoms or ions of a number of elements. Answer the following: (a) Which of the species are neutral? (b) Which are negatively charged? (c) Which are positively charged? (d) What are the conventional symbols for all the species?

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 74

Identify the elements represented by the following symbols and give the number of protons and neutrons in each case: $(\mathrm{a})_{10}^{20} \mathrm{X},(\mathrm{b})_{29}^{63} \mathrm{X},(\mathrm{c})_{47}^{107} \mathrm{X},(\mathrm{d})_{74}^{182} \mathrm{X}$ (e) $\frac{203}{84} \mathrm{X},$ (f) $\frac{234}{944}$

Wan Deng

Numerade Educator

Problem 75

Each of the following pairs of elements will react to form an ionic compound. Write the formulas and name these compounds: (a) barium and oxygen, (b) calcium and phosphorus, (c) aluminum and sulfur, (d) lithium and nitrogen.

Ronald Prasad

Numerade Educator

Problem 76

Match the descriptions $[(a)-(h)]$ with each of the following elements: $\mathrm{P}, \mathrm{Cu}, \mathrm{Kr}, \mathrm{Sb}, \mathrm{Cs}, \mathrm{Al}, \mathrm{Sr}, \mathrm{Cl}$
(a) A transition metal, (b) a nonmetal that forms a 3 ion, (c) a noble gas, (d) an alkali metal, (e) a metal that forms $a+3$ ion, (f) a metalloid, (g) an element that exists as a diatomic gas molecule,
(h) an alkaline carth metal.

Wan Deng

Numerade Educator

Problem 77

Explain why anions are always larger than the atoms from which they are derived, whereas cations are always smaller than the atoms from which they are derived. (Hint: Consider the electrostatic attraction between protons and electrons.)

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 78

(a) Describe Rutherford's experiment and how it led to the structure of the atom. How was he able to estimate the number of protons in a nucleus from the scattering of the $\alpha$ particles? (b) Consider the $^{23} \mathrm{Na}$ atom. Given that the radius and mass of the nucleus are $3.04 \times 10^{-15} \mathrm{m}$ and $3.82 \times 10^{-23} \mathrm{g},$ respectively, calculate the density of the nucleus in $\mathrm{g} / \mathrm{cm}^{3} .$ The radius of a $^{23} \mathrm{Na}$ atom is $186 \mathrm{pm} .$ Calculate the density of the space occupied by the electrons in the sodium atom. Do your results support Rutherford's model of an atom? [The volume of a sphere of radius $\left.r \text { is }(4 / 3) \pi r^{3} .\right]$

Wan Deng

Numerade Educator

Problem 79

Caffeine, shown here, is a psychoactive stimulant drug. Write the molecular formula and empirical formula of the compound.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 80

Acctaminophen, shown here, is the active ingredient in Tylenol. Write the molecular formula and empirical formula of the compound.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 81

What is wrong with the chemical formula for each of the following compounds: (a) magnesium iodate $\left[\mathrm{Mg}\left(\mathrm{IO}_{4}\right)_{2}\right],$ (b) phosphoric acid $\left(\mathrm{H}_{3} \mathrm{PO}_{3}\right)$ (c) barium sulfite (BaS), (d) ammonium bicarbonate $\left(\mathrm{NH}_{3} \mathrm{HCO}_{3}\right) ?$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 82

What is wrong with the names (in parentheses) for each of the following compounds: $\operatorname{SnCl}_{4}$ (tin chloride), (b) $\mathrm{Cu}_{2} \mathrm{O}\left[\text { copper(II) oxidel, }(\mathrm{c}) \mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}\right.$ (cobalt nitrate), (d) $\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ (sodium chromate)?

Wan Deng

Numerade Educator

Problem 83

Fill in the blanks in the following table.
$$\begin{array}{|l|c|c|c|r|r|}
\hline \text { Symbol } & & \frac{54}{26} \mathrm{Fe}^{2+} & & & \\
\hline \text { Protons } & 5 & & & 79 & 86 \\
\hline \text { Neutrons } & 6 & & 16 & 117 & 136 \\
\hline \text { Electrons } & 5 & & 18 & 79 & \\
\hline \text { Net charge } & & & -3 & & 0 \\
\hline
\end{array}$$

Nicole Smina

Numerade Educator

Problem 84

(a) Which elements are most likely to form ionic compounds? (b) Which metallic elements are most likely to form cations with different charges?

Wan Deng

Numerade Educator

Problem 85

Write the formula of the common ion derived from each of the following: (a) Li, (b) S, (c) I, (d) $\mathrm{N}$
(e) Al, (f) Cs, (g) $\widehat{M g}$

Ronald Prasad

Numerade Educator

Problem 86

Which of the following symbols provides more information about the atom: $^{23} \mathrm{Na}$ or $_{11} \mathrm{Na} ?$ Explain.

Wan Deng

Numerade Educator

Problem 87

Write the chemical formulas and names of binary acids and oxoacids that contain Group 7 A elements. Do the same for elements in Groups $3 \mathrm{A}, 4 \mathrm{A}, 5 \mathrm{A},$ and $6 \mathrm{A}$.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 88

Of the 118 elements known, only two are liquids at room temperature $\left(25^{\circ} \mathrm{C}\right) .$ What are they? (Hint: One element is a familiar metal and the other element is in Group 7 A.)

Wan Deng

Numerade Educator

Problem 89

For the noble gases (the Group 8 A elements), $^{4} \mathrm{He}$, $20 \mathrm{Ne}, \quad \frac{40}{18} \mathrm{Ar}, \frac{84}{36} \mathrm{Kr},$ and $_{54}^{132} \mathrm{Xe}$ (a) determine the number of protons and neutrons in the nucleus of each atom, and (b) determine the ratio of neutrons to protons in the nucleus of each atom. Describe any general trend you discover in the way this ratio changes with increasing atomic number.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 90

List the elements that exist as gases at room temperature. (Hint: Most of these elements can be found in Groups $5 \mathrm{A}, 6 \mathrm{A}, 7 \mathrm{A}, \text { and } 8 \mathrm{A} .)$

Wan Deng

Numerade Educator

Problem 91

The Group $1 \mathrm{B}$ metals, $\mathrm{Cu}, \mathrm{Ag},$ and $\mathrm{Au},$ are called coinage metals. What chemical properties make them specially suitable for making coins and jewelry?

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 92

The elements in Group 8 A of the periodic table are called noble gases. Can you suggest what "noble" means in this context?

Wan Deng

Numerade Educator

Problem 93

The formula for calcium oxide is $\mathrm{CaO}$. What are the formulas for magnesium oxide and strontium oxide?

Aishu Sanchula

Numerade Educator

Problem 94

A common mineral of barium is barytes, or barium sulfate (BaSO, $_{4}$ ). Because elements in the same periodic group have similar chemical properties, we might expect to find some radium sulfate (RaSO $_{4}$ ) mixed with barytes since radium is the last member of Group 2A. However, the only source of radium compounds in nature is in uranium minerals. Why?

Wan Deng

Numerade Educator

Problem 95

List five elements each that are (a) named after places, (b) named after people, (c) named after a color. (Hint: See Appendix 1.)

Aishu Sanchula

Numerade Educator

Problem 96

One isotope of a nonmetallic element has mass number 77 and 43 neutrons in the nucleus. The anion derived from the isotope has 36 electrons. Write the symbol for this anion.

Chareen Guzman

Numerade Educator

Problem 97

Fluorine reacts with hydrogen (H) and deuterium (D) to form hydrogen fluoride (HF) and deuterium fluoride (DF), where deuterium ( $^{2} \mathrm{H}$ ) is an isotope of hydrogen. Would a given amount of fluorine react with different masses of the two hydrogen isotopes? Does this violate the law of definite proportion? Explain.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 98

Predict the formula and name of a binary compound formed from the following elements: (a) Na and H,
(b) $\mathrm{B}$ and $\mathrm{O},$ (c) $\mathrm{Na}$ and $\mathrm{S},(\mathrm{d}) \mathrm{Al}$ and $\mathrm{F},(\mathrm{e}) \mathrm{F}$ and $\mathrm{O}$ (f) Sr and Cl.

Wan Deng

Numerade Educator

Problem 99

Identify each of the following elements: (a) a halogen whose anion contains 36 electrons, (b) a radioactive noble gas with 86 protons, (c) a Group $6 \mathrm{A}$ element whose anion contains 36 electrons, (d) an alkali metal cation that contains 36 electrons, (e) a Group 4A cation that contains 80 electrons.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 100

Write the molecular formulas for and names of the following compounds.

Wan Deng

Numerade Educator

Problem 101

Show the locations of (a) alkali metals, (b) alkaline earth metals, (c) the halogens, and (d) the noble gases in the following outline of a periodic table. Also draw dividing lines between metals and metalloids and between metalloids and nonmetals.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 102

Fill the blanks in the following table.
$$\begin{array}{|c|c|c|c|}
\hline \text { Cation } & \text { Anion } & \text { Formula } & \text { Name } \\
\hline & & & \text { Magnesium bicarbonate } \\
\hline & & \mathrm{SrCl}_{2} & \\
\hline \mathrm{Fe}^{3+} & \mathrm{NO}_{2}^{-} & & \\
\hline & & & \text { Manganese(II) chlorate } \\
\hline & & \mathrm{SnBr}_{4} & \\
\hline \mathrm{Co}^{2+} & \mathrm{PO}_{4}^{3-} & & \\
\hline \mathrm{Hg}_{2}^{2+} & 1^{-} & & \\
\hline & & \mathrm{Cu}_{2} \mathrm{CO}_{3} & \\
\hline & & & \text { Lithium nitride } \\
\hline \mathrm{Al}^{3+} & \mathrm{S}^{2-} & & \\
\hline
\end{array}$$

Hailey Tomashek

Hailey Tomashek

Numerade Educator

Problem 103

Some compounds are better known by their common names than by their systematic chemical names. Give the chemical formulas of the following substances: (a) dry ice, (b) table salt, (c) laughing gas, (d) marble (chalk, limestone), (e) quicklime, (f) slaked lime, (g) baking soda, (h) washing soda, (i) gypsum, (j) milk of magnesia.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 104

On p. 40 it was pointed out that mass and energy are alternate aspects of a single entity called massenergy. The relationship between these two physical quantities is Einstein's famous equation, $E=m c^{2}$ where $E$ is energy, $m$ is mass, and $c$ is the speed of light. In a combustion experiment, it was found that $12.096 \mathrm{g}$ of hydrogen molecules combined with $96.000 \mathrm{g}$ of oxygen molecules to form water and released $1.715 \times 10^{3} \mathrm{kJ}$ of heat. Calculate the corresponding mass change in this process and comment on whether the law of conservation of mass holds for ordinary chemical processes. (Hint: The Einstein equation can be used to calculate the change in mass as a result of the change in energy. $1 \mathrm{J}=1 \mathrm{kg} \mathrm{m}^{2} / \mathrm{s}^{2}$ and $c=3.00 \times 10^{8} \mathrm{m} / \mathrm{s}$

Wan Deng

Numerade Educator

Problem 105

Draw all possible structural formulas of the following hydrocarbons: $\mathrm{CH}_{4}, \mathrm{C}_{2} \mathrm{H}_{6}, \mathrm{C}_{3} \mathrm{H}_{8}, \mathrm{C}_{4} \mathrm{H}_{10},$ and $\mathrm{C}_{5} \mathrm{H}_{12}$.

Charles Thomas

Numerade Educator

Problem 106

(a) Assuming nuclei are spherical in shape, show that its radius $r$ is proportional to the cube root of mass number $(A) .$ (b) In general, the radius of a nucleus is given by $r=r_{0} A^{1 / 3},$ where $r_{0}$ is a proportionality constant given by $1.2 \times 10^{-15} \mathrm{m} .$ Calculate the volume of the $_{3}^{2} L$ i nucleus. (c) Given that the radius of a Li atom is $152 \mathrm{pm},$ calculate the fraction of the atom's volume occupied by the nucleus. Does your result support Rutherford's model of an atom?

Wan Deng

Numerade Educator

Problem 107

Draw two different structural formulas based on the molecular formula $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$. Is the fact that you can have more than one compound with the same molecular formula consistent with Dalton's atomic theory?

Charles Thomas

Numerade Educator

Problem 108

Ethane and acetylene are two gaseous hydrocarbons. Chemical analyses show that in one sample of ethane, $2.65 \mathrm{g}$ of carbon are combined with $0.665 \mathrm{g}$ of hydrogen, and in one sample of acetylene, $4.56 \mathrm{g}$ of carbon are combined with $0.383 \mathrm{g}$ of hydrogen.
(a) Are these results consistent with the law of multiple proportions? (b) Write reasonable molecular formulas for these compounds.

Wan Deng

Numerade Educator

Problem 109

A cube made of platinum (Pt) has an edge length of 1.0 $\mathrm{cm}$. (a) Calculate the number of $\mathrm{Pt}$ atoms in the cube. (b) Atoms are spherical in shape. Therefore, the Pt atoms in the cube cannot fill all of the available space. If only 74 percent of the space inside the cube is taken up by $\mathrm{Pt}$ atoms, calculate the radius in picometers of a Pt atom. The density of Pt is $21.45 \mathrm{g} / \mathrm{cm}^{3}$ and the mass of a single $\mathrm{Pt}$ atom is $3.240 \times 10^{-22} \mathrm{g}$. [The volume of a sphere of radius $\left.r \text { is }(4 / 3) \pi r^{3} .\right]$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 110

A monatomic ion has a charge of $+2 .$ The nucleus of the parent atom has a mass number of $55 .$ If the number of neutrons in the nucleus is 1.2 times that of the number of protons, what is the name and symbol of the element?

Wan Deng

Numerade Educator

Problem 111

In the following $2 \times 2$ crossword, each letter must be correct four ways: horizontally, vertically, diagonally, and by itself. When the puzzle is complete, the four spaces will contain the overlapping symbols of 10 elements. Use capital letters for each square. There is only one correct solution.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator