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Small-Group Discussion Questions '-- Key Terms '-- 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