See if you can organize the first 25 elements of the periodic table in order in the quiz below. The periodic table as we know ...

The noble gases (Helium, Neon, Argon etc.) were not discovered until much later, which explains why there was a periodicity of 7 and not 8 in Newlands table. Newlands did not leave any gaps for ...

Across a period from left to right, the covalent radius decreases. As you move from left to right across the periodic table, atoms have more electrons in their outer energy level and more protons ...