There are 118 elements in the periodic table, each with a unique symbol and atomic number. Symbol: A one or two-letter abbreviation used to represent the element. Atomic number: The number of ...

and all the elements in group 0 are unreactive non-metals. The zigzag, staircase, line in the diagram of the periodic table above separates the metals, on the left, from non-metals, on the right.

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 ...