The first 20 elements of
- the first 20 elements of the periodic table and their atomic number
- the first 20 elements of chemistry
- the first 20 elements of the periodic table and their electronic configuration
- the first 20 elements of the periodic table and their chemical symbols
- the first 20 elements of the periodic
- the first 20 elements of the periodic table in order
- the first 20 elements of the periodic table with atomic number
- the first 20 elements of the periodic table song
- the first 20 elements of the periodic table and their symbols
- the first 20 elements of the periodic table
