Chemistry Reference
In-Depth Information
allow predictions to be made about elements we
have not observed in action.
●
They react vigorously with halogens, such as
chlorine, to form metal halides, for example sodium
chloride (Figure 9.8).
sodium
2Na(
s
)
+
+
chlorine
Cl
2
(
g
)
sodium chloride
2NaCl(
s
)
→
→
a
Potassium reacts very vigorously with cold water.
Figure 9.8
A very vigorous reaction takes place when sodium burns in
chlorine gas. Sodium chloride is produced.
Considering the group as a whole, the further down
the group you go the more reactive the metals become.
Francium is, therefore, the most reactive Group I metal.
Table 9.1 shows the electronic structure of the
first three elements of Group I. You will notice in
each case that the outer energy level contains only
one electron. When these elements react they lose
this outer electron, and in doing so become more
stable, because they obtain the electron configuration
of a noble gas. You will learn more about the stable
nature of these gases later in this chapter (p. 143).
When, for example, the element sodium reacts
it loses its outer electron. This requires energy to
overcome the electrostatic attractive forces between the
outer electron and the positive nucleus (Figure 9.9).
b
An alkaline solution is produced when potassium reacts with water.
Figure 9.7
