What is a common reaction of the element Selenium?

Answer 1

nervousness

Answer 2

Chemically??

Mercury selenide (HgSe)
Hydrogen selenide (H2Se)
Selenium dioxide (SeO2)
Selenic acid (H2SeO4)
Selenous acid (H2SeO3)
Selenium sulfides: Se4S4, SeS2, Se2S6
Sodium selenite (Na2SeO3)
Zinc selenide (ZnSe)

Physically??

Selenium is toxic if taken in excess. Exceeding level of 400 micrograms per day can lead to selenosis.

Symptoms of selenosis include a garlic odor on the breath, gastrointestinal disorders, hair loss, sloughing of nails, fatigue, irritability and neurological damage.

Extreme cases of selenosis can result in cirrhosis of the liver, pulmonary edema and death.