Arsenic

Its symbol is As. Its atomic number is 33. Arsenic comes from the Greek word “arsenikos” which means male or masculine. It has been a known element since the ancient times. It was discovered by Albertus Magnus of Germany in 1250. This semimetallic element is known for being poisonous however it was discovered that some of its compounds are also medicinal.

Arsenic is very brittle, steel grey and is a crystalline semi-metallic (metalloid) solid. When heated, it rapidly oxidizes to arsenous oxide which gives a garlic odor. It also tarnishes in air. It is popularly known as a poisonous metalloid and is a favorite poison by murderers. It can pollute water, the environment, land, the human body and even healthy crops. Arsenic poisoning kills a human body by allosteric inhibition of essential metabolic enzymes. This leads to multi-system organ failure and eventually to death.

It is used as a doping agent, for insecticides, poisons, laser materials and hardening shots among others.

Astatine

Its symbol is At and is a radioactive chemical element. Its atomic number is 85. It belongs to the halogen group and is the heaviest element of the group. It comes from the word “astatos” which means unstable. It was discovered in 1940 at the University of California by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè of USA by bombarding bismuth with high-energy alpha particles. It was early researched at the Alabama Polytechnic Institute that’s why originally it was called alabamine.

Astatine exhibits the most metallic properties. One has to be careful with Astatine as this element is highly carcinogenic. It is extremely radioactive. Astatine is mostly found in minute amounts due to its short half life. It is produced by radioactive decay in nature.

Astatine normally doesn't present a risk to human beings as its presence in the biosphere is in minute amounts. However, it could possibly accumulate in the thyroid like iodine and it's toxicity is similar to that of iodine.

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