iodine and xenon

2.  Iodine is a chemical element with
symbol I and atomic number 53. The name is
from Greek ioeides, meaning violet or purple,
due to the color of elemental iodine vapor.
 Iodine and its compounds are primarily used
in nutrition, and industrially in the production
of acetic acid and certain polymers.
 Iodine is found on Earth mainly as the highly
water-soluble , which concentrates it
in oceans and brine pools. It is the
heaviest essential element.

3.  Iodine is required by higher animals for
synthesizing thyroid hormones, which contain the
element.
 Iodine was discovered by French chemist Bernard
Courtois in 1811. He was born to a manufacturer
of saltpeter.

5.  Xenon is a chemical element with
symbol Xe and atomic number 54. It is a colorless,
dense, odorless noble gas, that occurs in the Earth's
atmosphere in trace amounts.
 Naturally occurring xenon consists of eight stable
isotopes. There are also over 40 unstable isotopes that
undergo radioactive decay.
 Xenon is used in flash lamps and arc lamps, and as
a general anesthetic. Xenon is also being used to
search for hypothetical weakly interacting massive
particles and as the propellant for ion
thrusters in spacecraft.
 Xenon was discovered in England by the Scottish
chemist William Ramsay and English chemist Morris
Travers on July 12, 1898, shortly after their discovery
of the elements krypton and neon. They found xenon
in the residue left over from evaporating components
of liquid air.