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Small-Group Discussion Questions
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Key Terms
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iftHI 11/ tltt· kt·y /L'rll/\ u11d ro11repts t1111/ 11111111· others 11pp1•t11
atomic mo ~c; p. 130
atomic moss unit (u) p 129
atomic number (Z) p. 132
chemical fomily p 133
Dalton' atomic theor) p 120
electron p. 122
group p. 133
isoto~ p. 127
Lal\ of l\lultiple Proportions p. 120
111
139
1lt1• Glossary. L'sc your Gla.1 wn rt:eularfr
ma in group clements p. 134
mass number (A) p. 127
metal p 134
metalloid p. 134
neutron p. 125
nonmetal p. 134
nuclear model of the atom p. 124
nuclear S) mbol p. 127
nucleus p. 124
periods p. 133
plum pudding model p. 123
proton p. 125
representothe elements p. 134
Rutherford scnllering experiment p. 123
subatomic particle p. 122
transition clements p. 134
trans ition metals p. 134
Frequently Asked Questions
Q: What i\ the d11fere11ce he1we1•11tire111asl ofan isowpr um/
atomic 11ws.1!
A: Studenb often ha\e no trouble"' uh questions about isotope:. 11 hen stud} ing Section 5-4. In particular. questions such
as those posed in Acuve Example 5-1 are generally easy 10
answer at first. I lowcver. after studying Secllon 5-5, studcms
may become confused abou1 the difference between the muss
of a pec1fic i~olope of an element und lhc average atomic mass
of all of the natural!} occumng isotopes of an element. For
example. 12.01 u is the atomic muss of carbon. but ii is neither
the ma:.:. number of carbon-12 nor ils mass. Addit1onall). :you
cannot use the Jtomic mass of an element 10 detenmne the
number of neutrons in an isotope or thu1 elemenL The number
of neutrons is the difference bet ween the mass number (A) of a
specified isotope and the atomic number (Z) for the clement.
Q: Whm 1.1 the p11rp111·1 of Jucuti11g t 1il'llw111s in the pemulii·
table 11 /11/t leur11111g 11a111e-sy111bol pmn?
A: There are a couple of reasons\\ hy th1:. ii. beneficial. One
1s chat 111s u mcmor:r aid. Even though ii seems simpler to
memorize nu mes and S}mbols without referring to a periodic table. research on memor} shows that the oppo~lle ts
true. When you associate symbol~ wilh their posilions in lhc
periodic wble, ii helps you remember their namci.. Another
reason for doing this is that the 1 a Jue of the periodic table
cannot be overstated. You are usmg 11 nO\\ 1n Chapter 6 to
learn the system of naming chemical compounds; after that, it
\VIII help you in many other ways. For example. you will need
atomic musses 10 solve some of the problem:. in thi:. course.
The periodic rnble is a readily avai lable source of these value:.. Other applications of t he period ic table wi ll appear ai. the
course progresses. T he faster you are at locating an element's
posnion within the table. the more efficient you \\Ill be al
using the periodic table in these upcoming applications.
Q: H'/1111 1·0111111u11 errurs llw11/d I /oak ta ui:oid 1~/wn ll!arnmg
1wml! \y111hol pmrs?
A: The most common error while learning to write symbols
a nd for mulas is writing both lc11eri. in a two-letter elemental
symbol as ~upila ls. T he first leller is always a capital letter.
ff a second leuer b present. il is ahrnys wrillcn an lowerca e
The langu<1ge of chemistr) is ver> precise. and correctly \Hllten symbols are part of that language. II is also important to
learn the correct spelling of elemental names as you come 10
them. Floumw mslcad ofj/11or111e b the most common misspelli ng of un clementnl name.
Concept-Linking Exercises
Write a hm'f t/111 riptio11 uf tltt" ridutiu111/iipt 111111111g l'lll'lt IJ./ t/1< jn/1111rl11g grt111p1 of /t'flllS or pltr11ses. • I 11s11•1•rs to tire Cc111cep1-L111k11w L 11•rci.1e~ 1Jrt 1:11'1•11 r11 1111• ,•11d a} 1/w C'ltaptt!r.
I. Da lton ·~ atomic theory. nuclear model of the alom,
Rutherford') scattering C'<pcnments.
2. Electron. proton. neutron. ubulomic particles.
3. Atomu: mass unit. carbon-12. gram.
4. Isotopes. neutron. proton, mass numbe1. atomic number,
a1om 1c muss.
5. Periodic table. group:.. periods.
6. Muin group elemenb, transition elements. trans111011
metals, metal!>, nonmetals. meta llo1ds.
7. Atomic mass of an element. atomic mass of an
average atomic mass.
i~otopc.
Small-Group Discussion Questions
Smull·Grc111p DiH·11nlc111Qu.:ttw1111ir1·j11r i:rt111p ll'or.l """"' 111 cl<1ss
or umier 1/ir 11111dum·e cl/ u leader d11r1m:" d1.1c11.uic111 se1·111111
I. Define the Luw of Definite Composition. the L t\\. of
Con~crvu1ion
of Muss. and the La\\. of Multiple Propor·
uons. b.plarn how
theory
the~e
la\h lead to Dalton's atomic
2. Fill in the blanks in the following table. Do not use an}
references.
140
Chapter 5 Atomic Theory: The Nuclear Model of the Atom
Symbol
Charge Relative
to an Ell!Gtron
at 1-
Mass Relative
to a Hydrogen
Atom
ls Ila
Nuclear
Particle?
(YIN)
Electron
Proton
Neutron
3. I f the nucleus ofa single atom was bCalcd up Lo a diameter of 1 inch. what would be the diameter of an atom'?
Answer in USCS units.
4. When expressed to the full, unrounded correct number
of significant figures, the atomic mass ofziJlc is 65.38 u
and the atomic mass of nickel is 58.6934 u. Why docs
the number of significant figures vary among elements'?
Nickel has five naturally occurring isotopes, nickel-58.
-60. -6L -62. and -64. Which is most abundant?
Ho\\ do you know? How many electrons, protons. and
neutrons are in each nickel isotope?
5. A balloon is ril led with nitrogen ga:. 8Jld placed in a
is I bar. The volume of Lhc balloon is decreased until it
is I liter. The balloon and its contents are weighted. and
the gas is found to have a mass of 1.2 g. The experiment
is repeated with oxygen, fluorine, and chlorine gases.
What is the mass oflhe gas in each trial? Equal volumes
of gases a t the same pressure :rnd temperature have equal
nttmbers of molecules.
6. How many elements fa ll into each of the rollowing
cacegories'/ Use the periodic table 011 your shield when
answering this question. Period 4. main group elements. meta I&. U.S. Group SB. transit.ion element~.
Period 7. nonmetal:., I U PAC Group 16, rcprescnla tive
elements.
Construct a SCI or nash card!> with the symbols of each
of U1e 35 elements to be memorized on one side and their
nu mes on lhe olher side. (Make more or fewer cards if
your instructor requires you to memorize more or fewer
elemental symbols.) Split into pairs and practice giving
names for symbols and symbols for names u ntil each
person can repeat the entire set rapidly and accurately in
both direction!>.
refrigeration unit set at 2°C. The atmospheric pressure
Questions, Exercises, and Problems
Jmeracrn·e 1·usio11s of rhese problems 11w1• be am'g11ed by l'Ollr illstrncwr S11/11rl1ms j11r .t ' 11111/•,
1"
1
1 are ur the 111111 af the t:lw(Jter.
Q11e.mons other than /hose Irr the General Q111minns anti Mon• Cho/le11gl11g Prohll!lllS wctil11u are puirc•il in <'IJllSl!rttlll'I! udd-1!\'l!ll m1111ber
r1m1bi11atl1m.r. s11/11111111sfur the udd-mtmberl!d ques//(1/1~ urt' 11/sn ut t/ic>
end of th1· chapter
Section 5-1: Dalton's Atomic Theory
{!_- Accordmg to Dalton's atomic rheory. can more than
one compound be made from utoms of the same two
elements?
2. List tbc major point~ in Dalton's atomic theory.
.()Show that Dalton's atomic theory explain:. the Law of
Dclinitc Composition.
4.) How does Dalton·s atomic theory account for the Law of
Conservation of Mass·~
5 The chemical name for limescone. a compound of calcium. carbon. and oxygen. is calcium carbonate. When
heated. limestone decomposes into solid calcium oxide
and ga~cous carbon dioxide. From Lhe names of the
products. tell where you might find the atoms or each
clement after the reaction. How does Dallon's atomic
theory explain lhis?
6. The brilliance wi rh which magnesium burns makes it
idea l for use in marine flares and fireworks. Compare 1he
mass of magnesium Lhat burns with the mass or magnesium in the magnesium oxide ash that forms. Explain this
in terms ofalomic theory.
The white light in fireworks can
result from burning magnesium.
7 Sulfur and fluorine fo rm tH least cwo compounds SF4
and SF6 • Explain hO\\ these compounds can be ust:d as an
example of the Law of Multiple Proportions.
8. When 10.0 g of chlorine reacu. with mercury under varying conditions, the reaction consumes either 28.3 g or 56.6
g of mercury. No other combinations occur. Explain these
observations in terms of the Law of Multiple Proportions.
Section 5·2: The Electron
9. Advances in Lechnolo~')' and science often progress hand-
in-hand. Whal advance in technology was necessary to
set the slage for the discovery of the electron?
10. When J J. Thomson meas ured the deflection of a stream
of electrons in a magTietic field, he was able to demonstrate thal electrons were particles. but he was unable lo
determine the mass of an electron. Explain.
11. The mass of an electron 1s J/1837 of tile mass of a hydrogen atom. Express this fraction as a percentage. What
Questions, Exercises, and Problems
perceniagc of the mass of a hydrogen atom is due to the
renrnining subatomic purLiclc(s)?
26.
Name of
Element
12. What ib meant by stating that the charge of an electron ii.
1- ? What is the symbol or the electron?
;tLa
28
Phosphoru~
57
13. How can we account for the foct that. in the Rutherford
scancring experiment. some of the ulpha particle:. were
denected from their paths through the gold foil. and
some were even dellected buck at various angles'?
29
17. Describe the activity of electrons according to the plunetar) model of the arnm that appeared after the Rutherford scaucnngeAperiment.
18. The Rutherford experiment was performed and its con·
clusion:. reached before proton'> and neutrons were d1scoverec..I. When they were fount.I, why was it believed 1hu1
they were in the nucleus of the atom?
~omparc the three major parts ofao atom in charge
and mass
( 19
20. Which of the follO\\ ing applic:. to the electron'! (a) Charge =
1-: (b) Mass = I u: (c) Charge - O; (d) Mass = 0 u; (e)
Charge= I+.
Section 5-4: Isotopes
ll. Can 1wo different elements have the same atomic num-
ber? fapluin
Compare the number of proton~ and electron in an
atom. the numbe:r of protoni. and neutrons. and the number of clec1 ron~ and neutrons.
36
25
Aluminum
Section 5-5: Atomic Mass
Alll11111g'1 t/111 ftf uf IJlll'.\/lt111\ 1.1 ha11•tl 011111u1erw/ 111 Sut11m 5-5.
some porn u/ wme (/1tes1ians UI.flllllt tlwr you lww ul.w .11111/rt'c/
Sertio115·611111/ cu11 II.fl! the pt•rimllt- ttthft• u.1uw111rt1•11} 11tt11111c
What do we call the central part of an atom'!
16. What major conclubions were drawn from i he Ru thcrford
scattering experiment?
82
~Cu
14. How can we account for the fact that most of the alpha
parucles in the Rutherford cauering e:<periment passed
directly through a sohd sheet of gold?
n.
Nuclear Atomic Mass
Symbol Number Number Protons Neutrons Electrons
1
Section 5-3: The Nuclear Atom
and Subatomic Particles
15
140a
ma.Ht•s.
\zi\
-
What advantage docs the atonuc mass unit have over
grams when speaking oft he mass of an atom or a ~ub­
atom1c particle?
28. What il> an atomic mass unit?
l::J
The mass or an average atom of a certain element t'> 6 66
limes us great as the mas:. of un atom of carbon-12. Usmg
either the periodic table or the table of elements. 1dcn11fy
the clement.
30. T he average mass of boron atoms 1~ 10.81 u. How would
you explain \\hat th ts means 10 u friend \\ho had never
taken chembtry?
~~ The atomic masse~ or lhc natural isotopes of neon •.ire
19.99244 u, 20.99395 u, am! 2199138 u The averugc of
these three masses is 20.99259 u. The atomic mass of
neon i~ listed a~ 20.1797 u on the periodic table. Which
isotope do you expect is the most abundant m nature?
Explain
E.xplain why 1solopes of dilTurcnt clements can have the
same mass number. but 1so1opcs of the same clcmcn1 con not.
U . HO\\ man} protons. neutrons. and electrons are there in a
neutral atom of the isotope repre!>ented by ~ B'!
Q11estw11s !5 untl 26 From 1/Je mformat11111 J!ll't'll 111 the follml'lnR
table.1./11/ m u.111111111· h/1111/.s cu you e1111111tl1t111t lcwki11g llf 1111.1• reft'r·
l!llC'I! If tl11m• 11re 1111fi/lc•tl spU('t'S. (tJ/11111111! hr rt'fel'rmg 10 1•011r pemulw
table. As" last re.wri. check the tuhlt• of ele111e111.1 0111/ie Refere11cr
Page. All t11t1111111rt 11e11tral
lS.
Name of
Bement
Nuclear
Symbol
When neon gas Is within an
24
21
acUvatecl gas discharge tube,
reddish-orange light Is emitted.
122
72
37
II
17
12
32. A certain clement consists of two :stable isotope., The
first has an atomic mu:.s of 137 9068 u and a percentage
naturul abundance of0.09"'•· T he second ha'> an atomic
mas~ of 138.9061 u and a percentage natural abundance
of99 91% What as the atomic mass of the element?
140b
Chapter 5 Atomic Theory: The Nuclear Model of the Atom
JJ.
~
/
Tbe mas) of 60.4jYr1 of the atoms or an element is 68.9257
iu. There:: is only one other natural isotope of that element.
and its atomic:: mass is 70.9249 u. Calculate the average
atomic mass of the clement. Using lhc periodic table and/
or the rnble of Lhe elements. write its symbol and name.
34. Isotopic data for boron allO\\ lhe C~tlcula tion or its
alomic mass to the number of :.ignificant figures justified
by the measurement process. One analysis showed that
19.78% or boron atoms have an atomic mass or 10.0119
u, and the remaining Htoms have an atomic mass of
11.00931 u. Find the uveruge mass in us mony significant
figures as those data will allow.
Q11estwns JI tl1rrmi:h 36: Pert't'llfllJ(<' ab1111dm1ces and ll/01111r masses
(11) af the 1111111rul isu1opeJ. af011 l'le111e11111rt• gfre11. (a) C11/r11/111e the
aw11111 mllss of"'"'" t•l<•me111 from tliese daw. ( hJ Using otln•r i11;vr111uli11111ltu1 i.v umilalt/e '" 1•c111, idt•llfifI' the e/eml!llf.
Percentage Abundance
Atomic Mass (u)
36.
.'7.
38.
40.
51.82
48.18
106.904 1
108.9047
69.09
30.91
62.9298
64.9278
57.25
42.75
120.9038
122.9041
37.07
62.93
184.9530
186.9560
0.193
0.250
88.48
11.07
135.907
137.9057
139.9053
141.9090
67.88
26.23
1.19
3.66
1.08
57.9353
59.9332
60.9310
61.9283
63.9280
48. Give the atomic mass or the clement in each g iven group
and period. (a) Group SA/18. Period 3: (b) Group 3A/13.
Period 4; (c) Group 48/4, Period 4: (d) Group 2A/2. Period 3.
Section 5-7: Elemental Symbols
and the Periodic Table
' 4t) The name~. atomic numbers. or symbols of some or the
elements in Figure 5-19 <ire given in Table 5·4. Fill in
the open !)paces. referring on ly 10 a periodic table for <iny
information tha1 you need.
i@§iji Table of Elements
Name of Element
Atomic Number
Symbol of Elemeot
Mg
8
Phosphoru~
Ca
Zinc
Li
Nitrogen
16
53
Barium
K
10
Helium
Br
Ni
Tin
14
SU. The names. <ilom ic numbers. or symbols of some of 1he
Section 5-6: The Periodic Table
~I
How many elements are in Period 5 of Lhe periodic table?
Write the atomic numbers of the element:. in Group 3B/3.
42. Write the symbol of1he clcmen1 in each given group and
period. (t\) Group !All, Period 6; (b) Group 6A/16. Period
3: (c) Group 7817, Pcnod 4; (d) Group IA/ I. Period 2.
.n Locate i111hc periodic table e-acb clement whose atomic
number is given. and identify first the number of the pcnod
it is in and 1hen the number of the group: Ca) 20: lb) 14: le) 43.
.W. Lisi the symbols of 1hc elcmcats of each of the following:
(a) transi1ion metals in the fourth period; (b) metals in
the third period; (C::) nonmetals in Group 6A/16 or 7A/l7
'45. \:~::o:,:o~ ~:r::ii: ~::~~:cr~~~~:~:~l~:~::::~:~:c
\..:_
masses of I he clements whose atomic numbers arc 29, 55.
and 82.
elements in Figure 5-19 are given in Table 5·5. Fill in
the open spaces. referring only to a periodic 1able for any
information you need.
1§§¥11
Name of Bement
Atomic Number
Symbol of Element
Sodium
Pb
Aluminum
26
F
Boron
18
Silver
6
46. Write the a tomic number of the element in euch given
group and period. (a) Group 4A/14, Poriod 3; (b) Group
4A/l4. Period 2; (c) Group I B/ 11 . Period 4; (d) Group
2A/2, Period 3.
Copper
.n
Chlorine
Write the atomic masses of helium and uluminum.
Tnle of Elementa
Be
Krypton
Questions, Exercises, and Problems
Table 5-5
.. of Elements (Continued)
Name of Element
Atomic Number
Symbol of Bement
Mn
24
CobnlL
140c
r) Elements in the same column of the penodic table
have similar properties.
s) The element ror which Z = 38 is in both Group 2A/2
and the fifth period.
5J. The first experiment to suggest that an atom con:.isted
of smaller particles showed that one particle had a negative charge. From that fact, what could be said about
the cJiargc of other particles that might be present?
8()
General Questions
'-
SI. Distinguis.h precisely and in scientific terms the differences 11mong items in each of the following groups:
a) Atom. subatomic punicle
b) Electron. proton. neutron
c) Nuclear model orthe atom, nucleus
d) Atomic number. mass number
e) Chem1cu I symbol of an elemen t, nuclear symbol
f) Atom. isotope
g) Awnuc mass, atomic mass unit
h) Atomic mass of an clement. atomic mass of an isotope
i) Period. group. or fomily (in the periodic table)
j) Main group elemem, transition clement
r=.;\
Determine whether each statement that fol lows is true
\,..::\ or fulse.
'-
al Dalton proposed thut atoms or different elements
alwayi. combine on a one-to-one basis.
b) According to Dalton, all oxygen atoms have the same
diameter.
c) The mass or an electron 1s about the same as the mass
ofa proton.
d) There are subatom ic particles in addition to the electron, proton. and neutron.
e) The mass of an atom i~ uniformly distributed
throughout the atom.
f) Most of the particles fucd i11to the gold foi l in the
Rutherford experiment were not deflected.
g) The mas~es of the proton and electron are equal but
oppo&ite in sign.
h) Isotopes or an element have different electrical cha rges.
i) The atomic number of an element is the number of
particles in the nucleui. of an atom or that element.
j) An oxygen-16 atom has the same number of protons
us un oxygen-17 atom.
k) Thi! nuclei of nitrogen atoms have a different number
of protons from the nuclei of an) other clement.
I) Neutral 11toms orsutrur have a different number or
electrons from neutral atoms or any other element
m) l::.otopcs of different element) that exhibit the :.ame
mass number exhibit sim ilar chemical behavior.
n) The mass nwuber of u carbon-12 atom is exactly 12 g.
o) Periods are arranged vertically in the periodic table.
p) The atomic mas~ of the second element in the farthest
right column of1he periodic table is 10 u.
q) Nb is lhesymbol of the clemen t for which Z = 41.
More Challenging Problems
54. Sodium oxide and sodium peroxide are two compounds
made up of the elements sodium and o\ygen. Sixty-two
grams of sodi um oxide contains 46 g of sodiwn and 16 g
of oxygen; 78 g of sod ium peroxide has 46 I! of sodrn rn
and 32 g of oxygen. Show how these figures confirm the
Law of Multiple Proport ioni..
54'. Tuo comiiounds of mercury and chlorine are mercury(!)
c.hloride and mercury( II ) ch loride. TI1e amount of
mercury( I) cWoride that contains 71 g of chlorine has 402
g of mercury; the amount of mercury(! I ) chloride that has
71 g of chlorine has 201 gofmercury. Show how the Law
or Multiple Proportioni. il> il luwuted b) these quuntitiei..
56. TI1e CRC !T1.J11tilwak. a !urge reference book of chemical
and physical data. lists two isotopes of rubidium (Z = 37).
The atomic mass of72.IS°J., or rubidium a toms is 84.91 18 lL
Through a typographical oversight. the atomic mass of the
, \ second ii.otope ii. not printed. Calculate thot atomic mass.
l
57. \The element lanthanum has two stable isotopes. lantlrnnum-138 with un atomic mass of 137.9071 u und Janthanum-139 with an atomic mass of 138.9063 u. From the
atomic mass of La, 138.9 u. what conclusion can you make
about the relative percentage abundance of the 1sotopcs'I
5K. The atomic ma~s of lithium on u periodic table ia 6.94 u.
Lithium has two nalur-r:1 I isotopes with atomic masses or
6.10512 u anJ 7.01600 u. Calculate the percentage distri·
bution between the two isotopes.
Pure lithium
Is composed of
two isotopes.
59 When Thomson ident ified the electron. he found that
Lhe nitio of its charge Lo its mas!) (the e/m ra tio) was the
same regardle:ss of the elemenl from which the electron
came. This showed that the electron is a unique paruclc
that is found i11 atoms of all elements. Posnively charged
particles found al about the same time did not all have
the same e/m raLio. (Later it wus found Llrnt even different
atoms of the ~ame clement conta in positive particles that
have different c/m ra1ios.) What <.loes that suggest about
lhc mass, partich: charge. and minimum number of positive parucles from different elements?
140d
Chapter 5 Atomic Theory: The Nuclear Model of the Atom
carbon atom is 1.9 x 10
I g = 6.02 x 1011 u.
Ml. Why were cicn11s1s inclined lo Lhink of an atom as
a mtnmlurc solar ystem in the nuclear model of the
111om? \\'hat are the s1milarnics and differences bet\\een
electron:. in orbit around u nucleu~ and planets in orbit
around the sun?
b) Suggc!>t a rea.,on for the densit) of the atom being so
much larger than the density of either form of carbon.
were unknown until nearly a centur) after
the atomic theory. When the} were
d1~covered , it wa1. through e~perimcnts more closely
associated wnh physics than with chemistry. What
does this suggest about the chemical properues of
isotopes'!
oCJh
cm 1. As stated in Section 5-5.
a} Calculate the •nerage dens11y or a carbon atom.
botope~
Dalton
14
c) The radius of a carbon atom 1s roughl) I x 10~ times
!urger thun the radius of the nucleus. What is the volume of that nucleus" (1/1111: Volume is proportional to
the cube of the radiu~.)
propo~ed
d) Calculate the average density of the nucleus.
l'1 62. The elemen1 curbon occurs in two crystal forms. dia-
cl The radius of a period on this page is about 0.02 cm.
The volume of a sphere that site is 4 X 10 5 cm 1• Calcuhlle the mass ofthut sphere il'il were completely
fil led with carbon nuclei. Express the mass in tons.
mond and graphite. The dcnsi1y of the diamond form is
3.51 g/cm 1• and of graphite. 2.25 g/cm 3• The volume of a
Answers to Target Checks
Electrons and protons are electrically charged. but
neutrons have no charge (or zero charge). True: b. c. d. e. f.
I. The Law of Mulliple Proportions 1s confinned. The fixed
mass of '\ulfur is 1.0 g. The rauo of masses of oxygen =
1.0/0.5
= 2/1. which 1s a ratio of small whole numbers.
2. The remainder of the hydrogen atom must have a charge or
1-t· to balance the I charge or the electron. Cl+l + Cl-) = 0.
3.
(g)
4. All stotemcnt:. arc true.
S. (a} F-our Group JA/13 element!> are metals (Al. Ga. In.
Tl}. (bl Ten Period-4 elements are transition metals
(Sc through Zn).
Atoms are mostly made up of empt) space, so they arc
not hard. They are mall. and their shape is spherical.
a)
Answers to Practice Exercises
I. 19 protons, 19 electrons. 22neutrons;14K and ~ 1 K:
4.
A = 41 , Z = 19.
Main
Group or
2. (0.0759 X 6.0151223 u) + (0.9241 X 7.0160041 u) = 6.940 u
3. (0.9493 x 31.97207070 u) + (0.0076 X 32.97145843 u) +
(0.0429 X 33.96786665 u} + (0.0002 X 35.96705062 u) =
32.07 u
Symbol
N
Metal,
Nonmetal,
Atomic
Alomlc
lrlllSlllon
or
Number
Mall
Period
Group
Element
Metallokl
7
14.01
2
5A/15
Main
group
Nonmetal
ll
Mg
12
24.31
u
3
2A/2
Mam
group
Metal
Cr
24
52.00
u
4
58/5
Transiti on
Metal
5. Pb, lead: I lg. mercury: Mn. manganese: sodium. Na:
phosphorus. P. tin. Sn
Answers to Concept-Linking Exercises
>01111101· ha1·e /01111d mure
relutum1/11ps ur relt11ionships 01/1er tlrcm 1/ic
11111'.\ gil"t•fl Ill t/U:.11: Ullfll t'f.f
I. Dalton\ atomic theory proposed that mailer is compo cd of indivisible atoms. The nuclear model of the
atom resulted from Ruthcrford·s cattermg experiments.
TI1e model pictures the atom as a dense nucleus surrounded by electrons movmg 111orbit111 the otherwise
empt)' space outside the nucleus.
2. An atom contuin!> many particles (subatomic particles),
the most important of which are electrons, protons, and
neutrons.
3. One atom of carbon-12 has been a~signed a ma~ or 12
atomic mas!> units, u. Thu~ I u b. b) definition. exactl}
1/12 of the mass of a carbon-12 atom. Both the atomic
mass unit and lhc gram are mass units. 6.02 x l<P u = I g.
4. All utoms of an clement have the s.ame number of protons: this i ' the atomic number of lhe clement. Atoms of
the same clement lllU) have different numbers or neutron:.
and therefore different atomic musse::.. Atoms or an element with different numbers of neutrons are isotopes.
The mas ~ number of an atom is 1he sum of tl1e number of
protons plus the number of neutron~ .
Answers to Blue-Numbered Questions, Exercises, and Problems
nonmetals. include clements of atomic number 5. 14. 32.
33. 51. and 51. Transition metab are the element:. in the
B group:.. an areu that inclu<.les all the transnion elements
5. Horizontal row:. m the periodic table are periods. and
vertical columns arc groups.
6. Mam group clements urc those in the A groups (U.S.) of
the periodic table. und trunsition element:. arc those in the
B groups. In the periodic tttble. metals arc to the left of Lhc
stair-step line beginning between atomic numbcN 4 <tnd 5
in Period 2 and ending between atomic numbers 84 and 85
in Period 6, and the nonmetals are to the right of thi~
ltne. The mctal101<.ls, w11h propcrues of both metals and
140e
7. The term <tto111it· mu.1.1 actually refer) to a\eruge atomic
mass, but the word <11•t·m1:e 1s omitted The utom1e mass
or an element is the .1vcrage mass of a ll orits nnturnl
isotopes. The atomic muss ofun individual 1. otopc ofun
clement is the mass of an atom oflhal particular isotope
All atoms ofa particu lar 1&otope ha\e the :.arne mass.
Answers to Blue-Numbered Questions, Exercises, and Problems
I. Yes. see Figure 5-2.
27. The mas:. of 11 proton und neutron is close to I u. unc.1 6.02
x IO?J u = I g. It 1s more eon ..enient to use the u because
mass values expressed in u are not tin) fractions that
must be expressed in exponential notation.
3. The Law of Delin11e Compos11ion says that any compound
1s always made up of clements in the same proportion by
muss. Dalton"!. atomic theory C'-pla ins Lhis by staling llrnt
atoms different elements combine to form compounds.
29. 6.66 x 12.0 u = 79 9 u, Br
5. T he calcium atoms and '>Orne of Lhe oxygen atom' arc in
the calcium oxide. the carbon Jtoms and ~omc of the oxygen atoms are in the carbon d1ox1dc.
31. The atomic mus., of neon i'> less than the uvcrage of the
three atomic mas cs, so the 1Sotope with the lm.. est muss
must be prese111 in 1he greatest abundance.
7. The La\\ of Muluple Proporuons m this case states that
the same mass of sulfur combines with ma:.:.e:. of nuortnc
m the ratio of :.implc "hole number:.. 4 to 6.
33. 0.604 x 68.9257 u
Gu. gallium
or
9. The invention of the Crookes tube. n high-quality
vacuum tube.
X IOO'!to = 0.05444'Y.1: I00.00000 0.05444 - 99.94556'r,,
1837
13. Alpha particles .ind atomic nuclei are posiuvely charged.
As an alpha particle approached a nucleus. the repulsion
between Lhe po it1\.e charges dcllccted che aJpha purl iclc
from us path.
11.
35. 0.5182 x 106.9041u +0.4818 x 108.9047 u = 1079 u.
Ag,
I
15. The nucleus.
39. 0.00193 x 135 907 u + 0.00250 x 137.9057 u + 0.8848 x
139.9053 u + 0.1107 x 141.9090 u = 140.1 u. Ce. cerium
-'l. 18: 21. 39. 57. 89
43. (al Period -t. Group :!A/2: (b) Period 3, Group 4A/14.
(c) Period 5. Group 7017
45.
19. See Table 5-l.
49.
23. Ma:.s number i:. the sum or protons plus ncutrom. hot opes
of the same element huve different number:. of neutrons.
but the same number of protons. The -.urns must be diffcrcnL Atoms of c.lifferent clements 11111.11 have different numbers of protons. and they mu) have different numbers of
neutrons. An atom wnh one le:.s proton than another ma)
have one more neutron than the other. so their mass numbers would be the same. F'\umple: curbon-14 (6 proton~. 8
neutrons) and nitrogl!n- 14 (7 proton1>, 7 neutrons).
25.
Name of
Element
Nuclear Atomic
Symbol
Electrons
~ilver
37. 0.5725 x 120.9038 u + 0.4275 x 122.9041 u = 121.8 u.
b. antimony
17. The electrons were thought to truvel in circular orbits
around the nucleus.
21. No. the atom ic number is the number of protons, und all
utoms of an clement have the same number ofprotoni..
+ (I 000 0.604) x 70.9249 u - 69.7 u.
z = 29. 63.55 u. z - 55. 13:!.9 u: z = 82, 207.2 u
47. He, 4.003 u: Al. 26.98 u
Name of Element
Mugnesium
0 '1:ygcn
Phos:phorus
Calcium
Zinc
Lt1h1um
Nitrogen
Sulfur
Atomic Number
Symbol of Element
12
Mg
8
0
p
15
20
cj
JO
Zn
3
7
Li
N
16
s
Iodine
53
Bariw11
56
Bu
Pota:.s1um
19
10
K
2
lie
35
28
Br
Neon
candium
~;&
21
45
21
2-t
21
Germanium
~Ge
J:!
76
31
4-t
3:!
I lehurn
Bromine
Tin
'~.Sn
50
122
50
n
50
Nickel
Ch lorine
gc1
17
37
17
:!O
17
Tin
Sodium
ilN~t
II
23
II
11
II
Si licon
50
14
Ne
Ni
Sn
Si
140f
Chapter 5 Atomic Theory: The Nuclear Model of the Atom
52. True: b.• d, f.j, k, I, q, r. s. Fa lse: n. c, e, g, h,
1,
54. SixLeen grams of oxygen combines with 46 grams of
sod ium in sodium oxide. and 32 grams or oxygen combines with 46 grams of sodium in sodium peroxide. T he
ralio 16/32 reduces 10 112, a ratio of small, whole numbers.
56. 0.7215 x 84.9118 u + ll - 0.72 15)
x = 86.91 u
planets and the vast amo unl of empty space in the atom/
m. n, o, p.
53. Whal was lcfl hud lo have a positive chu rge lo account
for the neutrality of the complete atom.
xx u = 85.4678 u:
58. y x 6.10512 u + (1 y) x 7.01600 u = 6.94 u: y = 0.083;
8.3°/cial 6.10512 u: l 0.083 = 0.917: 91.7% at 7.01600 u
59. Different e/m ratioi. for positively charged particles from
different elemen1s indicate that, unlike the elec1ron. all
positively charged piirticles are not alike. The charge. the
mass. or both must vary from element 10 element. Tim
suggests the presence of al least two pan1clcs 10 varying
number ratios. One or both must have a positive charge:
others could be c:ilcctrically neutral.
60. The nuclear model of the atom is similar to the solar
system in that electrons orbit the nucleus as planets orbit
the sun. Both models arc similar in H:nns of the si1.e of the
nucleus/sun being large compared with the electrons/
•oulton apparently did not mtike any specific comment about the
d iamcicr or an <liom. bu1 he did propose lhat ull atoms of an c lcmeni
ore idcnt1cul in every respect. This wou ld include diameters.
solar system.
61. ChemicaJ properties of isotopes or an element are
identical.
62.
12.01 u
Ig
I Catom
ta) I Catom x 6.02 x 1021 u x 1.9 x 10 24 cm'
=
I. I x 10 1g/cm3
(b) In packing carbon atoms into a crystal there arc
spaces between the atoms. There arc no voids in a
single atom. (In fact. voids in diamond account
for 66% or the total volume. and in graphite, 78'V.1.)
(c)
(d)
1.9 x 10 l~cm~
=
( I x 1os)1
2
10 39
X
3
cm
12.01 u
I Cnuclcus
x
lg
I Cnucleus
, x
6.02 x J0· 3u 2 x 10 wcm'
_
(c) 4 x
5
10 cm
3
I
X
= 4 x 105 tons
x 10 16 g
I cmJ
X
= 1 X 1 0 ,~n/
Elem 3
1lb
I lon
454K X 2000 lb