7/31/2019 3992378400

1/3

Solutions to Homework 10CHE 1073-003 (Fall 2009)

Solutions to Homework 10 (Ch. 10 Modern Atomic Theory & the Periodic Table)

Paired exercises

1. a) H - 1 protonb) B - 5 protonsc) Sc - 21 protonsd) U - 92 protons

3. a) B - 1s22s22p1

b) Ti - 1s22s22p63s23p64s23d2

c) Zn - [Ar]4s23d10; ([Ar] = 1s22s22p63s23p6)d) Br - [Ar]3d104s24p5

e) Sr - [Kr]5s2

9.

a) 147N

b) 3517Cl

c) 6530Zn [Ar]

d)

91

40Zr [Kr]

1 of3

1s 2s 2px 2py 2pz

1s 2s 2px 2py 2pz 3s 3px 3py 3pz

4s 3dxz 3dyz 3dxy 3dz2 3dx2-y2

5s 4dxz 4dyz

7/31/2019 3992378400

2/3

Solutions to Homework 10CHE 1073-003 (Fall 2009)

e) 15753I [Kr]

(The specific orbitals are specified just for clarity. In reality, the threep orbitals have the sameenergy and the five dorbitals have the same energy, so from the electron's perspective, itdoesn't care which orbital it goes into as long as its empty.)

11. a) O 1s22s22p4

b) Ca 1s22s22p63s23p64s2 (or [Ar]4s2)c) Ar 1s22s22p63s23p6

d) Br 1s22s22p63s23p63d104s24p5 (or [Ar]3d104s24p5)

e) Fe 1s2

2s2

2p6

3s2

3p6

4s2

3d6

(or [Ar]4s2

3d6

)

13. a) Mg c) Nib) Ar d) Mn

25) Noble gases all have filled s andp orbitals in their outermost energy level.

29. a) 4 d) 7b) 6 e) 3c) 1

40) Period 4 Group 3B contains the first element with an electron in a d orbital.

Additional exercises

43) The valence energy level of an atom can be determined by looking at what period theelement is in. Period 1 corresponds to valence energy level 1, period 2 to valence energylevel 2, and so on. The number of valence electrons for elements 1 - 18 can be determined bylooking at the group number. for example, boron is under group 3A, therefore it has threevalence shell electrons.

44. a) valence energy level 2, 1 valence electron

b) valence energy level 3, 7 valence electronsc) valence energy level 3, 4 valence electronsd) valence energy level 3, 6 valence electronse) valence energy level 2, 2 valence electrons

45) Na+, F - and Ne all have 8 valence electrons

2 of3

4dxz 4dyz 4dxy 4dz2 4dx2-y2 5s 5px 5py 5pz

7/31/2019 3992378400

3/3

Solutions to Homework 10CHE 1073-003 (Fall 2009)

60) If element 36 is a noble gas, element 35 would be in Group 7A and 37 would be in Group1A.

67) Metals are located on the left side of the periodic table. The elements in Group 1A have

only one valence electron and those in Group 2A have only two valence electrons. It is fareasier for metals to lose their valence electrons to achieve a noble gas configuration ratherthan gaining valence electrons. That is why metals lose valence electrons to achieve a noblegas configuration.

Nonmetals are located on the right side of the periodic table where they are only 1 or 2electrons short of a noble gas configuration. In contrast to metals, it is easier for nonmetals togain valence electrons to achieve a noble gas configuration rather than losing valenceelectrons. Nonmetals therefore gain valence electrons to achieve a noble gas configuration.

3 of3