Group 1 of the periodic table is known as Alkali metal. Mainly six chemical elements are present in this groupnamely Lithium (Li), Sodium(Na), Potassium(K), Rubidium Rb), Caesium (Cs), and Francium(Fr).
The alkali metals are also called alkalis because when they react with water it forms strong bases which are capable of neutralizing acids.
The alkali metals are very reactive that they are usually found in nature in a combined state with other elements.
The alkali metals have a silver-like luster, and high ductility and they are good conductivity of heat and electricity and are usually associated with metals.
Francium(Fr) is the heaviest alkali metal because as we move down the group in a periodic table, the atomic size as well as the nuclear charge increase.
As we move from Li to Fr in group I, a new electron shell is added to each element, and the nuclear charge increases with an increase in the atomic number.