Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas. The elemental form was discovered by the French chemist Bernard Courtois in 1811.
Definition of CHOLLA. : any of numerous shrubby opuntias chiefly of the southwestern United States and Mexico that have needlelike spines partly enclosed in a papery sheath and cylindrical joints âcalled also cholla cactus.
The word âcitronellaâ describes both a tropical tree and a fragrant grass, as well as the oil that is extracted from the grass. Citronella oil is very popular around the world as an âall naturalâ mosquito and tick repellant, and a number of sprays, candles, and other products feature it prominently.