Vision (Definition) Vision is a feature of a person's brain that allows him to see. He must have normal eyes, optic nerves (that stretch from the eyes to the back of his brain), and visual cortex (the vision center in the brain), in order to see properly. An ophthalmologist is a doctor specializing in vision. ...Read more.
The halogens or halogen elements (/ËhÃ¦lÉdÊÉn, ËheÉª-, -loÊ-, -ËdÊÉn/) are a group in the periodic table consisting of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.
Noun. 1. halon-a compound in which the hydrogen atoms of a hydrocarbon have been replaced by bromine and other halogen atoms; very stable; used in fire extinguishers although it is thought to release bromine that depletes the ozone layer.organic compound-any compound of carbon and another element or a radical.alon. n. 1. (Chemistry) any of a class of chemical compounds derived from hydrocarbons by replacing one or more hydrogen atoms by bromine atoms and other hydrogen atoms by other halogen atoms (chlorine, fluorine, or iodine).