The alkali metals, found in group 1 of the periodic table, are very reactive metals that do not occur freely. The outer shell of these metals has only one electron. They are prepared to lose that electron in ionic bonding.
Among the most reactive metals are Alkali metals. It’s due to their larger atomic radii and low ionization energies. They tend to donate their electrons in reactions and have an oxidation state. These metals are characterized by the silvery and soft texture.
For example sodium metal when comes in contact with oxygen it burns out rapidly.
They are less dense than most elements and have low boiling and melting points. They float on the water because of their low density. These elements have large atomic radii and weak metallic bonding, so they have these characteristics.
Group 1 elements are good reducing agents because they have an ns1 configuration and are easy to oxidize. All of the alkali metals are found in nature, but not in their pure forms.
Most combine with oxygen and silica to form minerals in the Earth and are readily mined as they are of relatively low densities and thus don’t sink.