1

Chapter 3 Electronic Structure and the Periodic Law

3.5Another Look at the Periodic Table

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

2

Distinguishing Electrons

The last and highest energy electron found in an element.

Nobel gas configurations can be used to write abbreviated electronic configurations. Instead of writing the configurations in their entirety, the symbols for the noble gases are used in brackets to represent the electrons found in their configuration.

3

Abbreviated Electronic Configuration Form

For example, take Group 1A(1), which contains Li, Na, K, Rb, Cs, and Fr with the electronic configuration for the first four elements shown below.

ElementSymbol

Conventional Form

Li 1s2,2s1

Na 1s2,2s2,2p6,3s1

K 1s2,2s2,2p6,3s1,3p6,4s1

Rb 1s2,2s2,2p6,3s1,3p6,4s2,3d10,4p6,5s1

4

Abbreviated Electronic Configuration Form

ElementSymbol

Conventional Form

Li 1s2,2s1

Na 1s2,2s2,2p6,3s1

K 1s2,2s2,2p6,3s1,3p6,4s1

Rb 1s2,2s2,2p6,3s1,3p6,4s2,3d10,4p6,5s1

The abbreviated form can be written using the noble gas configuration as a shorthand notation in brackets.

AbbreviatedForm

[He]2s1

[Ne]3s1

[Ar]4s1

[Kr]5s1

5

Abbreviated Electronic Configuration Form

ElementSymbol

Conventional Form

Li 1s2,2s1

Na 1s2,2s2,2p6,3s1

K 1s2,2s2,2p6,3s1,3p6,4s1

Rb 1s2,2s2,2p6,3s1,3p6,4s2,3d10,4p6,5s1

Notice that each of these elements has a single electron in the valence shell, is located in the s subshell, and similar chemical properties of elements in the same group.

6

Periodic Table divided into subshells

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

s subshells

d subshells p subshells

f subshells

7

Metals, Nonmetals, and Metalloids

The heavy zigzag line separates metals and nonmetals.• Metals are located to

the left.• Nonmetals are located

to the right. • Metalloids are located

along the heavy zigzag line between the metals and nonmetals.

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

8

Metals • are shiny and ductile.• are good conductors of heat and electricity.

Nonmetals• are dull, brittle, and poor conductors.• are good insulators.

Metalloids• are better conductors than nonmetals, but not

as good as metals.• are used as semiconductors and insulators.

Properties of Metals, Nonmetals, and Metalloids

9

Comparing a Metal, Metalloid, and Nonmetal

10

Identify each of the following elements as

1) metal 2) nonmetal 3) metalloid

A. sodium ____

B. chlorine ____

C. silicon ____

D. iron ____

E. carbon ____

Learning Check

11

Identify each of the following elements as

1) metal 2) nonmetal 3) metalloid

A. sodium 1 metal

B. chlorine 2 nonmetal

C. silicon 3 metalloid

D. iron 1 metal

E. carbon 2 nonmetal

Solution

12

Match the elements to the description.

A. Metals in Group 4A(14) 1) Sn, Pb 2) C, Si 3) C, Si, Ge, Sn

B. Nonmetals in Group 5A(15) 1) As, Sb, Bi 2) N, P 3) N, P, As, Sb

C. Metalloids in Group 4A(14) 1) C, Si, Ge, 2) Si, Ge 3) Si, Ge, Sn, Pb

Learning Check

13

Match the elements to the description.

A. Metals in Group 4A (14)1) Sn, Pb

B. Nonmetals in Group 5A(15) 2) N, P

C. Metalloids in Group 4A(14) 2) Si, Ge

Solution