Fluorine as an element is extremely reactive and toxic.

Fluorine is the most electronegative element and is extremely reactive, requiring great care in handling.

Strontium is a soft metal and is extremely reactive upon contact with water.

The metal is extremely reactive and pyrophoric, reacting with water even at 116 C ( 177 F).

Free radicals are extremely reactive and short-lived.

Ozone is a highly toxic and extremely reactive gas.

She was, so Mars had been informed, extremely reactive to changes in the Hero's mental and emotional states.

These hydrons do not exist in a free state: they are extremely reactive and are solvated by water.

The problem is that fluorine gas is extremely reactive.

The substances are extremely reactive, therefore potentially dangerous, and some consider them impractical.