Trends in Group 1

Note: Even though Hydrogen will appear above Lithium on the periodic table it is not considered a part of Group 1.

Group 1 elements are known as Alkali Metals.

They are called s-block elements because their highest energy electrons appear in the s subshell.

Progressing down group 1, the atomic radius increases due to the extra shell of electrons for each element.

Going down the group, the first ionisation energy decreases. There is more shielding between the nucleus and the outer electrons and the distance between the nucleus and the outer electron increases and therefore the force of attraction between the nucleus and outer most electrons is reduced.

Generally the melting point of the alkali metals decreases down the group. This is because as the ions get larger the distance between the bonding electrons and the positive nucleus gets larger and reduces the overall attraction between the two. For similar reasons the electronegativity decreases.

The reactions of the elements with water become more vigorous down the group.

When they do react they produce hydroxides and hydrogen.