Everything Science Grade 10

5.2 CHAPTER 5. THE PERIODIC TABLE

Alkali metals

Alkali earth metals

Transition metals

Group 13Group 14Group 15Group 16HalogensNoble gases

Figure 5.3: Groups on the periodic table

A few points to note about the groups are:

• Although hydrogen appears in group 1, it is not an alkali metal.


• Group 15 elements are sometimes called the pnictogens.


• Group 16 elements are sometimes known as the chalcogens.


• Thehalogensand thealkali earth metalsare very reactive groups.


• Thenoble gasesareinert(unreactive).

See video: VPasj at http://www.everythingscience.co.za

The following diagram illustrates some of the key trends in the groups of the periodic table:
group number
1
2 13 14 15 16 17

18

Atomic

radius

Ionization

energy

Electro-

negativity

Melting and

boiling point

Density

Figure 5.4: Trends in the groups on the periodic table.

Table 5.2 summarises the patterns or trends in the properties of the elements in group 1.
Similar trends are observed for the elements in the other groups of the periodic table. We
can use the information in 5.2 to predict the chemical properties of unfamiliar elements.
For example, given the element Francium (Fr) we can say that its electronic structure will
be [Rn] 7 s^1 , it will have a lower first ionisation energy than caesium (Cs) and its melting and
boiling point will also be lower than caesium.
You should also recall from chapter 2 that the metals are found on the left of the periodic
table, non-metals are on the right and metalloids are found on the zig-zag line that starts at
boron.

100 Chemistry: Matter and materials