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.
Haloalkanes are alkanes that contain one or more members of the halogen family. The halogens found in organic molecules are chlorine, bromine, fluorine, and iodine.Some texts refer to this class of compounds as halogenoalkanes or alkyl halides.This text will frequently use both haloalkane and alkyl halide, so it's important to remember that they are the same thing.he halogens found in organic molecules are chlorine, bromine, fluorine, and iodine. Some texts refer to this class of compounds as halogenoalkanes or alkyl halides. This text will frequently use both haloalkane and alkyl halide, so it's important to remember that they are the same thing.