Features of Groups
- The vertical columns in the periodic table starting from top to bottom are called groups. There are 18 groups in the periodic table.
- Based on the common characteristics of elements in each group, they can be grouped as various families.
|2||Alkaline earth metals|
|3 to 12||Transition metals|
|16||Oxygen Family (or) Chalcogen family|
- The Lanthanides and Actinides, which form part of Group 3 are called inner transition elements.
- Except ‘Group 18’, all the elements present in each group have the same number of electrons in their valence shell and thus have the same valency.
- For example, all the elements of group 1 have one electron in their valence shells (1s¹). So, the valency of all the alkali metals is ‘1’
- As the elements present in a group have identical valence shell electronic configurations, they possess similar chemical properties.
- The physical properties of the elements in a group such as melting point, boiling point and density vary gradually.
- The atoms of the ‘Group 18’ elements have stable electronic configuration in their valence shells and hence they are unreactive.