Bromine

Bromine is the only liquid nonmetallic element. It is a heavy,
volatile, mobile, dangerous reddish-brown liquid. The red vapor
has a strong unpleasant odor and the vapor irritates the eyes and
throat. It causes severe burns upon contact with the skin. In
concetrated form, it is a serious health hazard, and maximum
safety precautions should be taken when handling it. Bromine is
used in agricultural chemicals, dyestuffs, chemical intermediates
and flame-retardants. Most is used to prepare 1,2-dibromoethane,
which is used as an anti-knock agent in combustion engines.
Bromine is obtained by treating brines from wells in Michigan and
Arkansas with chlorine, or through extraction from seawater.
Chemical formula = Br. Molecular weight = 79.90 g/mol.