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Chemistry 2012

JOHN E. MCMURRY, ROBERT C. FAY, JORDAN FANTINI

Chapter 2

Atoms, Molecules, and Ions

Educators


Problem 1

Compounds A and B are colorless gases obtained by combining sulfur with oxygen. Compound A results from combining 6.00 g of sulfur with 5.99 g of oxygen, and compound B results from combining 8.60 g of sulfur with 12.88 g of oxygen. Show that the mass ratios in the two compounds are simple multiples of each other.

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Problem 2

The gold foil Rutherford used in his scattering experiment had a thickness of approximately 0.005 mm. If a single gold atom has a diameter of $29 \times 10^{-8} {cm}$ how many atoms thick was Rutherford’s foil?

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Problem 3

A small speck of carbon the size of a pinhead contains about $10^{19}$ atoms, the diameter of a carbon atom is $15 \times 10^{-10} {m}$ and the circumference of the Earth at the equator is 40,075 km. How many times around the Earth would the atoms from this speck of carbon extend if they were laid side by side?

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Problem 4

The isotope $\frac{75}{34} {Se}$ is used medically for the diagnosis of pancreatic disorders. How many protons, neutrons, and electrons does an atom of $\frac{75}{34} {Se}$have?

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Problem 5

Chlorine, one of the elements in common table salt (sodium chloride), has two main isotopes, with mass numbers 35 and 37. Look up the atomic number of chlorine, tell how many neutrons each isotope contains, and give the standard symbol for each.

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Problem 6

An atom of element X contains 47 protons and 62 neutrons. Identify the element, and write the symbol for the isotope in the standard format.

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Problem 7

Copper metal has two naturally occurring isotopes: copper-63 (69.15%; isotopic mass = 62.93 amu) and copper-65 (30.85%; isotopic mass = 64.93 amu). Calculate the atomic mass of copper, and check your answer in a periodic table.

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Problem 8

Based on your answer to Problem 2.7, how many atoms of copper are in an old penny made of pure copper and weighing 2.15 g?

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Problem 9

What is the mass in grams of each of the following samples?
(a) 1.505 mol of Ti (b) 0.337 mol of Na (c) 2.583 mol of U

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Problem 10

How many moles are in each of the following samples?
(a) 11.51 g of Ti (b) 29.127 g of Na (c) 1.477 kg of U

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Problem 11

Write a balanced nuclear equation for each of the following processes:
(a) Beta emission from ruthenium$1-106 : \quad \frac{106}{44} {Ru} \rightarrow$ $_{-1}^{0}{e}$ $+?$
(b) Alpha emission from bismuth$-189 : : 89 \mathrm{Bi} \rightarrow \frac{4}{2} \mathrm{He}+?$
(c) Electron capture by polonium$-204 :^{204} \mathrm{Po}+_{-1}^{0} \mathrm{e} \rightarrow ?$

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Problem 12

What particle is produced by decay of thorium-214 to radium-210? $^{214} \mathrm{Th} \rightarrow^{210} \mathrm{Ra}+?$

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Problem 13

Identify the isotopes involved, and tell what type of decay process is occurring in the following nuclear reaction:

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Problem 14

a) Of the two isotopes$^ {173}{Au}$ and $^{199} {A} {u}$ , one decays by $\beta$ emission and one decays by \alpha emission. Which does which?
b) Of the two isotopes $^{186} {Pb}$ and $^{206} {Pb}$ , one is nonradioactive and one decays by
positron emission. Which is which?

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Problem 15

Draw the structural formula of methylamine, ${CH}_{5} {N}$, a substance responsible for the odor of rotting fish. The carbon atom is bonded to the nitrogen atom and to three hydrogens. The nitrogen atom is bonded to the carbon and two hydrogens.

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Problem 16

Methionine, one of the 20 amino acid building blocks from which proteins are made, has the following structure. What is the chemical formula of methionine? In writing the formula, list the element symbols in alphabetical order and give the number of each element as a subscript.

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Problem 17

Which of the following drawings represents a collection of hydrogen peroxide (${H}_{2} {O}_{2}$) molecules? The red spheres represent oxygen atoms and the ivory spheres represent hydrogen.

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Problem 18

Adrenaline, the so-called “flight or fight” hormone, can be represented by the following ball-and-stick model. What is the chemical formula of adrenaline? (Gray = C, ivory = H, red = O, blue = N)

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Problem 19

Which of the following compounds would you expect to be ionic and which molecular (covalent)?
(a) LiBr (b) SiCl$_{4}$ (c) BF$_{3}$ (d) CaO

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Problem 20

Which of the following drawings is most likely to represent an ionic compound and which a molecular (covalent) compound? Explain.

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Problem 21

Give systematic names for the following compounds:
(a) CsF (b) ${K}_{2}{O}$ (c) CuO (d) BaS (e) ${BeBr}_{2}$

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Problem 22

Write formulas for the following compounds:
(a) Vanadium(III) chloride (b) Manganese(IV) oxide
(c) Copper(II) sulfide (d) Aluminum oxide

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Problem 23

Three binary ionic compounds are represented on the following periodic table: red with red, green with green, and blue with blue. Name each, and tell its likely formula.

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Problem 24

Give systematic names for the following compounds:
(a) ${NCl}_{3}$ (b) ${P}_{4} {O}_{6}$ (c) ${S}_{2} {F}_{2}$ (d) ${SeO}_{2}$

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Problem 25

Write formulas for compounds with the following names:
(a) Disulfur dichloride (b) Iodine monochloride
(c) Nitrogen triiodide

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Problem 26

Give systematic names for the following compounds:

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Problem 27

Give systematic names for the following compounds:
(a) ${Ca}({ClO})_{2}$ (b) ${Ag}_{2} {S}_{2} {O}_{3}$ (c) ${NaH}_{2} {PO}_{4}$
(d) ${Sn}({NO}_{3})_{2}$ (e) ${Pb}({CH}_{3} {CO}_{2})_{4}$ (f) $({NH}_{4})_{2} {SO}_{4}$

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Problem 28

Write formulas for the following compounds:
(a) Lithium phosphate (b) Magnesium hydrogen sulfate
(c) Manganese(II) nitrate (d) Chromium(III) sulfate

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Problem 29

The following drawings are those of solid ionic compounds, with red spheres representing the cations and blue spheres representing the anions in each.
Which of the following formulas are consistent with each drawing?
(a) LiBr (b) ${NaNO}_{2}$ (c) ${CaCl}_{2}$
(d) ${K}_{2} {CO}_{3}$ (e) ${Fe}_{2}({SO}_{4})_{3}$

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Problem 30

What two elements are thought to be the first ones formed in the big bang?

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Problem 31

In the following drawings, red spheres represent cations and blue spheres represent anions. Match each of the drawings (a)–(d) with the following ionic compounds:
(i) $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}$ (ii) $\mathrm{Li}_{2} \mathrm{CO}_{3}$
(iii) $\mathrm{FeCl}_{2}$ (iv) $\mathrm{MgSO}_{4}$

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Problem 32

If yellow spheres represent sulfur atoms and red spheres represent oxygen atoms, which of the following drawings shows a collection of sulfur dioxide ($SO_2$) units?

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Problem 33

Assume that the mixture of substances in drawing (a) undergoes a reaction. Which of the drawings (b)–(d) represents a product mixture consistent with the law of mass conservation?

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Problem 34

If red and blue spheres represent atoms of different elements, which two of the following drawings illustrate the law of multiple proportions?

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Problem 35

Which of the following three drawings represents a neutral Na atom, which repreents a Ca atom with two positive electrical charges $\left(\mathrm{Ca}^{2+}\right),$ and which represents an $\mathrm{F}$ atom
with one minus charge (F $)$ ?

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Problem 36

Give molecular formulas corresponding to each of the following ball-and-stick molecular representations (red = O, gray = C, blue = N, ivory = H). In writing the formula, list the elements in alphabetical order.
(a) Alanine (an amino acid)
(b) Ethylene glycol (automobile antifreeze)
(c) Acetic acid (vinegar)

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Problem 37

Isotope A decays to isotope E through the following series of steps, in which the products of the individual decay events are themselves radioactive and undergo further decay until a stable nucleus is ultimately reached. Two kinds of processes are represented, one by the shorter arrows pointing right and the other by the longer arrows pointing left.
(a) To what kind of nuclear decay process does each kind of arrow correspond?
(b) Identify and write the symbol X for each isotope in the series:

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Problem 38

How does Dalton’s atomic theory account for the law of mass conservation and the law of definite proportions?

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Problem 39

What is the law of multiple proportions, and how does Dalton’s atomic theory account for it?

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Problem 40

A sample of mercury with a mass of 114.0 g was combined with 12.8 g of oxygen gas, and the resulting reaction gave 123.1 g of mercury(II) oxide. How much oxygen was left over after the reaction was complete?

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Problem 41

A sample of CaCO, was heated, causing it to form CaO and $\mathrm{CO}_{2}$ gas. Solid CaO remained behind, while the $\mathrm{CO}_{2}$ escaped to the atmosphere. If the $\mathrm{CaCO}_{3}$ weighed 612 $\mathrm{g}$ and the CaO weighed 343 g, how many grams of $\mathrm{CO}_{2}$ were formed in the reaction?

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Problem 42

Benzene, ethane, and ethylene are just three of a large number of hydrocarbons—compounds that contain only carbon and hydrogen. Show how the following data are consistent with the law of multiple proportions.

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Problem 43

In addition to carbon monoxide (CO) and carbon dioxide $\left(\mathrm{CO}_{2}\right),$ there is a third compound of carbon and oxygen called carbon suboxide. If a 2.500 g sample of carbon suboxide contains 1.32 g of C and 1.18 g of O, show that the law of multiple proportions is followed.

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Problem 44

The atomic mass of carbon (12.011 amu) is approximately 12 times that of hydrogen (1.008 amu).
(a) Show how you can use this knowledge to calculate possible formulas for benzene, ethane, and ethylene (Problem 2.42).
(b) Show how your answer to part (a) is consistent with the actual formulas for benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right),$ ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right),$ and
ethylene $\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)$

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Problem 45

What is a possible formula for carbon suboxide (Problem 2.43)?

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Problem 46

If the atomic mass of an element is $x,$ what is the mass in grams of $6.02 \times 10^{23}$ atoms of the element?

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Problem 47

If $6.02 \times 10^{23}$ atoms of element $Y$ have a mass of 83.80 $\mathrm{g}$ , what is the identity of $\mathrm{Y}$ ?

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Problem 48

If the atomic mass of an element is $x,$ what is the mass in grams of $3.17 \times 10^{2}$ atoms of the element?

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Problem 49

If $4.61 \times 10^{21}$ atoms of element $Z$ have a mass of 0.815 g, what is the identity of $Z ?$

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Problem 50

A compound of zinc and sulfur contains 67.1% zinc by mass. What is the ratio of zinc and sulfur atoms in the compound?

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Problem 51

There are two compounds of titanium and chlorine. One compound contains 31.04% titanium by mass, and the other contains 74.76% chlorine by mass. What are the ratios of titanium and chlorine atoms in the two compounds?

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Problem 52

In methane, one part hydrogen combines with three parts carbon by mass. If a sample of a compound containing only carbon and hydrogen contains 32.0 g of carbon and 8.0 g of hydrogen, could the sample be methane? If the sample is not methane, show that the law of multiple proportions is followed for methane and this other substance.

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Problem 53

In borane, one part hydrogen combines with 3.6 parts boron by mass. A compound containing only hydrogen and boron contains 6.0 g of hydrogen and 43.2 g of boron. Could this compound be borane? If it is not borane, show that the law of multiple proportions is followed for borane and this other substance.

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Problem 54

What is the difference between an atom’s atomic number and its mass number?

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Problem 55

What is the difference between an element’s atomic number and its atomic mass?

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Problem 56

The subscript giving the atomic number of an atom is often left off when writing an isotope symbol. For example, $^{13} \mathrm{C}$ is often written simply as $^{13} \mathrm{C}$ Why is this allowable?

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Problem 57

Iodine has a lower atomic mass than tellurium (126.90 for iodine, 127.60 for tellurium) even though it has a higher atomic number (53 for iodine, 52 for tellurium). Explain.

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Problem 58

Copper has two naturally occurring isotopes, including $^{65}$ Cu. Look at the periodic table and tell whether the second isotope is $^{63} \mathrm{Cu}$ or $^{66} \mathrm{Cu} .$

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Problem 59

Sulfur has four naturally occurring isotopes, including $^{33} \mathrm{S}$ $^{34} \mathrm{S} and $^{36} \mathrm{S}. Look at the periodic table and tell whether the fourth isotope is $^{32} \mathrm{S}$ or $^{35} \mathrm{S}$

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Problem 60

Give the names and symbols for the following elements:
(a) An element with atomic number 6
(b) An element with 18 protons in its nucleus
(c) An element with 23 electrons

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Problem 61

The radioactive isotope cesium-137 was produced in large amounts in fallout from the 1985 nuclear power plant disaster at Chernobyl, Ukraine. Write the symbol for this isotope in standard format.

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Problem 62

Write symbols for the following isotopes:
(a) Radon-220
(b) Polonium-210
(c) Gold-197

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Problem 63

Write symbols for the following isotopes:
(a) Z = 58 and A = 140
(b) Z = 27 and A = 60

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Problem 64

How many protons, neutrons, and electrons are in each of the following atoms?
a) $\frac{15}{7} \mathrm{N}$ b) $\frac{60}{27} \mathrm{Co}$ c) $\frac{131}{53} \mathrm{I}$
d) $\frac{142}{58} \mathrm{Ce}$

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Problem 65

How many protons and neutrons are in the nucleus of the following atoms?
(a) $^{27} \mathrm{Al}$ (b) $^{32} \mathrm{S}$ (c) $^{64} \mathrm{Zn}$
(d) $^{207} \mathrm{Pb}$

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Problem 66

Identify the following elements:
a) $\stackrel{24}{12} \mathrm{X}$ b) $\frac{58}{28} x$ c)$\frac{104}{46} x$
d) $\frac{183}{74} \mathrm{X}$

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Problem 67

Identify the following elements:
a) $\frac{202}{80} {X}$ b) $\frac{195}{78} {X}$ c) $\frac{184}{76} {X}$
d) $\frac{209}{83} {X}$

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Problem 68

Which of the following isotope symbols can’t be correct?
$^{18}_{9} \mathrm{F}$ $^{12}_{5} \mathrm{C}$ $^{18}_{8} \mathrm{O}$ $^{11}_{5} \mathrm{BO}$

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Problem 69

Which of the following isotope symbols can't be correct?
$^{14}_{7} {Ni}$ $^{131}_{54} {Xe}$ $^{54}_{26} {Fe}$ $^{73}_{23} {Ge}$ $^{1}_{2} {He}$

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Problem 70

Naturally occurring boron consists of two isotopes: $^{10}$ ${B}(19.9 \%)$ with an isotopic mass of 10.0129 amu and $^{11}$ ${B}(80.1 \%)$ with an isotopic mass of 11.00931 amu. What is the atomic mass of boron? Check your answer by looking at a periodic table.

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Problem 71

Naturally occurring silver consists of two isotopes: $^{107} \mathrm{Ag}$ (51.84%) with an isotopic mass of 106.9051 amu and $^{109} \mathrm{Ag}$ (48.16%) with an isotopic mass of 108.9048 amu.
What is the atomic mass of silver? Check your answer in a periodic table.

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Problem 72

Magnesium has three naturally occurring isotopes: $^{24} \mathrm{Mg}$ (23.985 amu) with 78.99% abundance, $^{25} \mathrm{Mg}$ (24.986 amu) with 10.00% abundance, and a third with 11.01% abundance. Look up the atomic mass of magnesium, and then calculate the mass of the third isotope.

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Problem 73

A sample of naturally occurring silicon consists of $^{28} \mathrm{SI}$ (27.9769 amu), $^{29} \mathrm{SI}$ and $^{30} \mathrm{SI}$ (29.9738 amu). If the atomic mass of silicon is 28.0855 amu and the natural abundance of $^{29} \mathrm{SI}$ is 4.68%, what are the natural abundances $^{28} \mathrm{SI}$ and $^{30} \mathrm{SI}?$

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Problem 74

Positron emission and electron capture both give a product nucleus whose atomic number is 1 less than the starting nucleus. Explain.

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Problem 75

What is the difference between an particle and a helium atom?

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Problem 76

Why does beta emission raise the atomic number of the product while positron emission lowers the atomic number?

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Problem 77

Why do nuclei that are neutron rich emit b particles, but nuclei that are neutron poor emit a particles or positrons or undergo electron capture?

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Problem 78

Complete and balance the following nuclear equations:
a) $^{126}_{50} {Sn}\rightarrow \stackrel{0}{-1} {e}+?$ b) $^{210}_{88} {Ra}\rightarrow \stackrel{4}{2} {He}+?$
c) $^{77}_{37} {Rb}\rightarrow \stackrel{0}{-1} {e}+?$ d) $^{76}_{36} {Kr}\rightarrow \stackrel{0}{-1} {e}+?$

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Problem 79

Complete and balance the following nuclear equations:
a)$^{90}_{38} {Sr}\rightarrow_{-1}^{0} e+?$ b) $^{247}_{100} {Fm}\rightarrow_{4}^{2} He+?$
c) $^{49}_{25} {Mn}\rightarrow_{1}^{0} e+?$ c) $^{37}_{18} {Ar}\rightarrow_{-1}^{0} e+?$

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Problem 80

What particle is produced in each of the following decay reactions?
a) $^{188}_{80} \mathrm{Hg} \rightarrow^{188}_{79} \mathrm{Au}+?$
b) $^{218} _{85}\mathrm{At} \rightarrow^{214}_{83}\mathrm{Bi}$
c) $_{78}^{170} \mathrm{Pt} \rightarrow^{166}_{76} \mathrm{Os}+?$

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Problem 81

What particle is produced in each of the following decay reactions?
a) $_{11}^{24} \mathrm{Na}\rightarrow \stackrel{24}{12} \mathrm{Mg}+?$
b) $_{60}^{135} \mathrm{Nd} \rightarrow ^{135}_{59} \mathrm{Pr}+?$
c) $_{170}^{78} \mathrm{PT} \rightarrow ^{166}_{76} \mathrm{Os}+?$

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Problem 82

Write balanced nuclear equations for the following processes:
(a) Alpha emission of $^{162} \mathrm{Re}$
(b) Electron capture of $^{138} \mathrm{Sm}$
(c) Beta emission of $^{188} \mathrm{W}$
(d) Positron emission of $^{165} \mathrm{Ta}$

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Problem 83

Write balanced nuclear equations for the following processes:
(a) Beta emission of $^{157} \mathrm{Eu}$
(b) Electron capture of $^{126} \mathrm{Ba}$
(c) Alpha emission of $^{146} \mathrm{Sm}$
(d) Positron emission of $^{125} \mathrm{Ba}$

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Problem 84

Of the two isotopes of tungsten, $^{160} \mathrm{W}$ and $^{185} \mathrm{W}$ one decays by $\beta$ emission and one decays by $\alpha$ emission. Which does which? Explain.

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Problem 85

Of the two isotopes of iodine, $^{136} \mathrm{I},$ and $^{122} \mathrm{I},$ one decays by $\beta$ emission and one decays by positron emission. Which does which? Explain.

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Problem 86

Americium-241, a radioisotope used in smoke detectors, decays by a series of 12 reactions involving sequential loss of $\alpha, \alpha, \beta, \alpha, \alpha, \beta, \alpha, \alpha, \alpha, \alpha, \alpha,$ and $\beta$ particles. Identify each intermediate nucleus and the final stable product nucleus.

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Problem 87

Radon-2222 decays by a series of three $\alpha$ emissions and two $\beta$ emissions. What is the final stable nucleus?

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Problem 88

Thorium-232 decays by a 10 -step series, ultimately yielding lead-208. How many $\alpha$ particles and how many $\beta$ particles are emitted?

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Problem 89

How many $\alpha$ particles and how many $\beta$ particles are emitted in the 11 -step decay of $^{235} \mathrm{U}$ into $^{207} \mathrm{Pb}$ ?

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Problem 90

What is the difference between a covalent bond and an ionic bond? Give an example of each.

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Problem 91

Which of the following bonds are likely to be covalent and which ionic? Explain.
(a) B...Br (b) Na...Br (c) Br...Cl (d) O...Br

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Problem 92

The symbol CO stands for carbon monoxide, but the symbol Co stands for the element cobalt. Explain.

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Problem 93

Correct the error in each of the following statements:
(a) The formula of ammonia is NH3.
(b) Molecules of potassium chloride have the formula KCl.
(c) Cl$^{-}$ is a cation.
(d) ${CH}_{4}$ is a polyatomic ion.

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Problem 94

How many protons and electrons are in each of the following ions?
(a) ${Be}^{2+}$ (b) ${Rb}^{+}$ (c) 5$e^{2-}$ (d) ${Au}^{3+}$

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Problem 95

What is the identity of the element X in the following ions?
(a) $X^{2+},$ a cation that has 36 electrons
(b) $X^{-},$ an anion that has 36 electrons

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Problem 96

The structural formula of isopropyl alcohol, better known as “rubbing alcohol,” is shown. What is the chemical formula of isopropyl alcohol?

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Problem 97

Lactic acid, a compound found both in sour milk and in tired muscles, has the structure shown. What is its chemical formula?

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Problem 98

Butane, the fuel used in disposable lighters, has the formula $\mathrm{C}_{4} \mathrm{H}_{10}$ The carbon atoms are connected in the sequence C¬C¬C¬C, and each carbon has four covalent bonds. Draw the structural formula of butane.

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Problem 99

Cyclohexane, $\mathrm{C}_{6} \mathrm{H}_{12}$ is an important starting material used in the industrial synthesis of nylon. Each carbon has four covalent bonds, two to hydrogen and two to other carbons.
Draw the structural formula of cyclohexane.

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Problem 100

Isooctane, the substance in gasoline from which the term octane rating derives, has the formula $\mathrm{C}_{8} \mathrm{H}_{18}$ Each carbon has four covalent bonds, and the atoms are connected in the sequence shown. Draw the complete structural formula of isooctane.

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Problem 101

Fructose, ${C}_{6} {H}_{12} {O}_{6}$ is the sweetest naturally occurring sugar and is found in many fruits and berries. Each carbon has four covalent bonds, each oxygen has two covalent bonds, each hydrogen has one covalent bond, and the atoms are connected in the sequence shown. Draw the complete structural formula of fructose.

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Problem 102

Write formulas for the following binary compounds:
(a) Potassium chloride (b) Tin(II) bromide
(c) Calcium oxide (d) Barium chloride
(e) Aluminum hydride

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Problem 103

Write formulas for the following compounds:
(a) Calcium acetate (b) Iron(II) cyanide
(c) Sodium dichromate (d) Chromium(III) sulfate
(e) Mercury(II) perchlorate

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Problem 104

Name the following ions:
(a) ${Ba}^{2+}$ (b) ${Cs}^{+}$ (c) ${V}^{3+}$
(d) ${HCO}_{3}^{-}$ (e) ${NH}_{4}^{+}$ (f) ${Ni}^{2+}$
(g) ${NO}_{2}$ (h) ${ClO}_{2}$ (i) ${Mn}^{2+}$
(j) ${ClO}_{4}$

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Problem 105

Name the following binary molecular compounds:
(a) ${CCl}_{4} \quad$ (b) ${ClO}_{2}$
(c) ${N}_{2} {O} \quad$ (d) ${N}_{2} {O}_{3}$

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Problem 106

What are the formulas of the compounds formed from the following ions:
(a) ${Ca}^{2+}$ and ${Br}^{-}$
(b) ${Ca}^{2+}$ and ${SO}_{4}^{2-}$
(c) Al'$^{3+}$ and ${SO}_{4}^{2-}$

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Problem 107

What are the formulas of the compounds formed from the following ions:
(a) ${Na}^{+}$ and ${NO}_{3}^{-}$ (b) ${K}^{+}$ and ${SO}_{4}^{2-} \quad$ (c) ${Sr}^{2+}$ and ${Cl}^{-}$

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Problem 108

Write formulas for compounds of calcium with each of the following:
(a) chlorine (b) oxygen (c) sulfur

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Problem 109

Write formulas for compounds of rubidium with each of the following:
(a) bromine (b) nitrogen (c) selenium

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Problem 110

Give the formulas and charges of the following ions:
(a) Sulfite ion (b) Phosphate ion
(c) Zirconium(IV) ion (d) Chromate ion
(e) Acetate ion (f) Thiosulfate ion

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Problem 111

What are the charges on the positive ions in the following compounds?
(a) ${Zn}({CN})_{2}$ (b) ${Fe}({NO}_{2})_{3}$
(c) ${Ti}({SO}_{4})_{2}$ (d) ${Sn}_{3}({PO}_{4})_{3}$
(e) ${Hg}_{2} {S}$ (f) ${MnO}_{2}$
(g) ${KIO}_{4}$ (h) ${Cu}({CH}_{3} {CO}_{2})_{2}$

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Problem 112

Name the following binary compounds of nitrogen and oxygen:
(a) ${NO} $ (b) ${N}_{2} {O}$ (c) ${NO}_{2}$
(d) ${N}_{2} {O}_{4} $ (e) ${N}_{2} {O}_{5}$

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Problem 113

Name the following binary compounds of sulfur and oxygen:
(a) ${SO} $ (b) ${S}_{2} {O}_{2} $ (c) ${S}_{5} {O}$
(d) ${S}_{7} {O}_{2} $ (e) ${SO}_{3}$

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Problem 114

Fill in the missing information to give formulas for the following compounds:
a) ${Na}_{?} {SO}_{4}$ b) ${Ba}_{?}({PO}_{4})_{?}$ (c) ${Ga}_{?}({SO}_{4})_{?}$

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Problem 115

Write formulas for each of the following compounds:
(a) Sodium peroxide
(b) Aluminum bromide
(c) Chromium(III) sulfate

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Problem 116

Germanium has five naturally occurring isotopes: $^{70} {Ge}$ 20.5%, 69.924 amu; 72Ge, 27.4%, 71.922 amu; $^{77} {Ge}$ 7.8%, 72.923 amu; : $^{74} {Ge}$ , 36.5 \%, 73.921 {amu} ;$ and $^{76} {Ge}, 7.8 \%, 75.921$ amu. What is the atomic mass of germanium?

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Problem 117

Fluorine occurs naturally as a single isotope. How many protons, neutrons, and electrons are present in deuterium fluoride $(^{2} {HF}) ?(\text { Deuterium is }^{2} {H.})$

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Problem 118

Ammonia $({NH}_{3})$ and hydrazine $({N}_{2} {H}_{4})$ are both compounds of nitrogen and hydrogen. Based on the law of multiple proportions, how many grams of hydrogen would you expect 2.34 g of nitrogen to combine with to yield ammonia? To yield hydrazine?

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Problem 119

If 3.670 g of nitrogen combines with 0.5275 g of hydrogen to yield compound X, how many grams of nitrogen would combine with 1.575 g of hydrogen to make the same compound? Is X ammonia or hydrazine (Problem 2.118)?

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Problem 120

Identify the following atoms:
(a) A halogen with 53 electrons
(b) A noble gas with $A=84$

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Problem 121

Hydrogen has three isotopes $(^{1} {H},^{2} {H}, \text { and }^{3} {H})$ , and chlorine has two isotopes $\left(^{35} {Cl} \text { and }^{37} {Cl}\right) .$ How many isotopic kinds of HCl are there? Write the formula for each, and tell how many protons, neutrons, and electrons each contains.

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Problem 122

Prior to 1961, the atomic mass unit was defined as 1/16 the mass of the atomic mass of oxygen; that is, the atomic mass of oxygen was defined as exactly 16 amu. What was the mass of a $^{12} \mathrm{C}$ atom prior to 1961 if the atomic mass of oxygen on today's scale is 15.9994 amu?

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Problem 123

What was the mass in atomic mass units of a $^{40} \mathrm{Ca}$ atom prior to 1961 if its mass on today’s scale is 39.9626 amu? (See Problem 2.122).

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Problem 124

The molecular mass of a compound is the sum of the atomic masses of all atoms in the molecule. What is the molecular mass of acetaminophen $({C}_{8} {H}_{9} {NO}_{2}\right),$ the active ingredient in Tylenol?

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Problem 125

The mass percent of an element in a compound is the mass of the element (total mass of the element’s atoms in the compound) divided by the mass of the compound (total mass of all atoms in the compound) times 100%. What is the mass percent of each element in acetaminophen? (See
Problem 2.124.)

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Problem 126

Radioactive $^{100} \mathrm{Tc}$ decays to form $^{100} \mathrm{Mo}$ . There are two possible pathways for this decay. Write balanced equations for both.

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Problem 127

$^{226} \mathrm{Ac}$ can decay by any of three different nuclear processes: a emission, b emission, or electron capture. Write a balanced nuclear equation for the decay of $^{226} \mathrm{Ac}$by each process.

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Problem 128

Tetrahydrofuran, an organic substance used as a solvent in many pharmaceutical processes, has the formula ${C}_{4} {H}_{8} {O}$ . In tetrahydrofuran, the four C atoms are bonded in a row, each C atom is bonded to two H atoms, each H atom is bonded to one C atom, and the O atom is bonded to two C
atoms. Write a structural formula for tetrahydrofuran.

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Problem 129

In an alternate universe, the smallest negatively charged particle, analogous to our electron, is called a blorvek. To determine the charge on a single blorvek, an experiment like Millikan’s with charged oil droplets was carried out and the following results were recorded:
Droplet Number Charge (C)
1 7.74 $10^{-16}$
2 4.42 $10^{-16}$
3 2.21 $10^{-16}$
4 4.98 $10^{-16}$
5 6.64$ 10^{-16}$
(a) Based on these observations, what is the largest possible value for the charge on a blorvek?
(b) Further experiments found a droplet with a charge of $5.81 \times 10^{-16} \mathrm{C}$ . Does this new result change your answer to part (a)? If so, what is the new largest value for the blorvek's charge?

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