Radon is a chemical element and gas naturally arising in the atmosphere of earth.
It is a radioactive, colorless, odorless, tasteless gas. Its atomic number is 86 and its symbol is Rn. It was discovered by Fredrich Ernst Dorn, a German physicist in 1900. He discovered that the radium (radioactive element) delivers radon gas as it decomposes.
It was later isolated by Sir William Ramsay and Robert Whytlaw-Gray in 1910.