The Periodic Table is a well-organized chart that contains all 118 known elements in the universe. These elements are the ...

This story appears in the May 2013 issue of National Geographic magazine. N. Nitrogen. Atomic number seven. Unnoticed, untasted, it nevertheless fills our stomachs. It is the engine of agriculture ...

The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...