Chemistry – The Periodic Table - Group VII properties | e-Consult

Fluorine is the most reactive halogen due to its small atomic size and high electronegativity. Its small size allows it to approach and interact more readily with other atoms, while its high electronegativity means it has a strong tendency to attract electrons. This combination makes it much more likely to gain an electron and form a negative ion compared to chlorine, which is larger and less electronegative.

One practical application that takes advantage of fluorine's high reactivity is in the production of hydrofluoric acid (HF). HF is used as a cleaning agent for glass and also in the etching of silicon in the semiconductor industry. It reacts readily with glass (silicon dioxide) to dissolve it, due to the strong interaction between fluorine and silicon.