When a small piece of sodium is placed in a petri dish with water and phenolphthalein, the sodium becomes a molten ball and darts around the dish, leaving a pink trail. The reactions of potassium, ...

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.

It is its willingness to lose an electron completely and form a positively charge ion that makes caesium the most reactive metal in the periodic table, and yes I am including its relative francium!

118 Elements and Their Symbols and Atomic Numbers: The periodic table is a well-organized chart that contains all the known elements in the universe.These elements are building blocks of matter ...