1 to 20 elements of periodic table with atomic number atomic m symbol memorise first 20 elements first 20 elements of periodic table make a tabulation of elements and their atomic m of first 20 elements atomic number of the first 20 elements first 20 elements of the periodic table periodic table of elements symbols atomic m of elements 1 to 30 with 20 elements name symbol valency atomic what are the first 20 elements names atomic theory structure of an atom