Which element is the most reactive?

Top of group 7 (The halogens) are very reactive (e.g Fluorine). If you are looking at metals, the Group 1 Alkali metals are very reactive. As you move down the group them react more violently with water for example. (e.g. Rubidium, Caesium, Francium).

The most reactive element is Caesium. This is because it has many electron shells and only one electron in its outer shell, meaning the electrostatic forces of attraction between positively charged protons and the negatively charged electron is weak, so the electron is given up the easiest, meaning it is the most reactive.

Fluorine is the most reactive element in the periodic tbale

Flourine- fluorine is the most reactive non metal

The group 1 elements are the most reactive going in down the column from least to most

potassium is the most reactive element