Page 76 - Theory and Problems of BEGINNING CHEMISTRY

CHAP. 4] ELECTRONIC CONFIGURATION OF THE ATOM 65

ELECTRONIC STRUCTURE AND THE PERIODIC TABLE
4.25. Write detailed electronic configurations for (a)N,(b)P,(c) As, and (d) Sb. What makes their chemical
properties similar?
2
2
Ans. (a)1s 2s 2p 3
2
2
2
6
(b)1s 2s 2p 3s 3p 3
6
2
2
10
2
6
2
(c) 1s 2s 2p 3s 3p 4s 3d 4p 3
2
6
10
10
2
2
6
2
6
2
(d)1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 3
2
3
Their outermost electronic configurations are similar: ns np .
2
4
2
6
2
4.26. What neutral atom is represented by each of the following configurations: (a)1s 2s 2p 3s 3p ,
2
2
2
6
6
3
2
2
2
(b)1s 2s 2p , and (c)1s 2s 2p 3s 3p 4s ?
Ans. (a)S (b)N (c)Ca
4.27. Write the detailed electronic configuration for La (atomic number = 57) in shortened form.
2
Ans. La [Xe] 6s 5d 1
4.28. Write the electronic configuration of atoms of each of the following elements, using the periodic table as
a memory aid: (a) Si, (b)V,(c)Br,(d)Rb.
6
2
6
2
2
2
2
2
10
6
2
Ans. (a)1s 2s 2p 3s 3p 2 (c)1s 2s 2p 3s 3p 4s 3d 4p 5
2
6
2
2
6
10
2
2
6
2
2
2
6
6
(b)1s 2s 2p 3s 3p 4s 3d 3 (d)1s 2s 2p 3s 3p 4s 3d 4p 5s 1
4.29. Write the electronic configuration of atoms of each of the following elements, using the periodic table as
a memory aid: (a) As, (b) Ni, (c) Pd, and (d) Ge.
2
6
10
6
2
6
2
2
2
6
2
2
6
2
2
10
Ans. (a)1s 2s 2p 3s 3p 4s 3d 4p 3 (c)1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 8
2
6
10
2
6
2
2
6
2
2
2
2
6
(b)1s 2s 2p 3s 3p 4s 3d 8 (d)1s 2s 2p 3s 3p 4s 3d 4p 2
Supplementary Problems
4.30. State the octet rule in terms described in this chapter.
Ans. A state of great stability is a state in which the outermost s and p subshells are filled and no other subshell
of the outermost shell has any electrons.
4.31. List all the ways given in this chapter to determine the order of increasing energy of subshells.
Ans. The n + l rule, the energy-level diagram (Fig. 4-5) and the periodic table. (There are also some mnemonics
given by other texts.)
4.32. How many different drawings, like those in Fig. 4-4, are there for the 4f orbitals?
Ans. There are seven, corresponding to the seven f orbitals in a subshell (Table 4-5). General chemistry students
are never asked to draw them, however.
4.33. What are the advantages of using the periodic table over the other ways of determining the order of increasing energy
in subshells given in Problem 4.31?
Ans. The periodic table is generally available on examinations, it is easy to use after a little practice, it allows one
to start at any noble gas, it reminds one of the 5d electron added before the 4f electrons (at La), and it tells
by the number of elements in each block how many electrons are in the subshell.