Symbol

As

Atomic Number

33

Atomic Mass

74.9216

Family

Group 15 (Va) Nitrogen Pronunciation

AR-se-nick

Overview

Arsenic compounds have been known since at least the days of Ancient Greece and Rome (thousands of years ago). They were used by physicians and poisoners. The compound most often used for both purposes was arsenic sulfide (As₂S₃).

Arsenic was first recognized as an element by alchemists. Alchemy was a kind of pre-science that existed from about 500 B.C. to about the end of the 16th century. People who studied alchemy—alchemists—wanted to find a way of changing lead, iron, and other metals into gold. They were also looking for a way to have eternal life. Alchemy contained too much magic and mysticism to be a real science, but alchemists developed a number of techniques and produced many new materials that were later found to be useful in modern chemistry.

A small amount...