The number of the group identifies the column of the standard periodic table in which the element appears.
Group 1 contains the alkali metals ( lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium(Fr).)
Group 2 contains the alkaline earth metals ( beryllium (Be),magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra) )
Group 3: Scandium (Sc) and yttrium (Y)