Everything Science Grade 10

CHAPTER 5. THE PERIODIC TABLE 5.2

Element^73 Li^73 Na^73 K^73 Rb^73 Cs

Electron structure [He] 2 s^1 [Ne] 3 s^1 [Ar] 4 s^1 [Kr] 4 s^1 [Xe] 5 s^1

Group 1 chlorides

LiCl NaCl KCl RbCl CsCl

Group 1 elements all form halogen com-

pounds in a 1:1 ratio

Group 1 oxides

Li 2 O Na 2 O K 2 O Rb 2 O Cs 2 O

Group 1 elements all form oxides in a 2:1 ratio

Atomic radius Increases as you move down the group.

First ionisation energy Decreases as you move down the group.

Electronegativity Decreases as you move down the group.

Melting and boiling point Decreases as you move down the group.

Density Increases as you move down the group.

Table 5.2: Summary of the trends in group 1

Exercise 5 - 2

1. Use Table 5.2 and Figure 5.4 to help you produce similar tables for group

2 and group 17.

2. The following two elements are given. Compare these elements in terms

of the following properties. Explain the differences in each case.^2412 Mg

and^4020 Ca.

a. Size of the atom (atomic radius)

b. Electronegativity

c. First ionisation energy

d. Boiling point

3. Study the following graph and explain the trend in electronegativity of the

group 2 elements.

0

0. 5

1. 0

1. 5

Be Mg Ca Sr Ba

4. Refer to the elements listed below:

Chemistry: Matter and materials 101