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.
Comments. Submit. Nopal cactus, also called prickly pear, is a familiar sight on roadsides and fields across much of the United States. This family of pad-forming cacti has been used in many ways by different cultures since ancient times.