Just four years before Mendeleev announced his periodic table, Newlands noticed that there were similarities between elements with atomic weights that differed by seven. He called this The Law of ...

The periodic table is a well-organized chart that contains all the known elements in the universe. These elements are ...

neon and xenon (1898). It was debated whether the 'inert' monoatomic gases belonged to the periodic table owing to their lack of 'chemical properties'; elements coming late to the party ...