A silver halide is one of the compounds formed between silver
and one of the halogens - silver bromide (AgBr), chloride
(AgCl), iodide (AgI), and two forms of silver fluorides. As a
group, they are often referred to as the silver halides, and are
often given the pseudo-chemical notation AgX. Although most
silver halides involve silver atoms with oxidation states of +1
(Ag+), silver halides in which the silver atoms have oxidation
states of +2 (Ag2+) are known, of which silver(II) fluoride is
the only known stable one. The light-sensitive chemicals used in
photographic film and paper are silver halides. Silver halides
are used in photographic film and photographic paper, as well as
radiographic film and paper, where silver halide crystals in
gelatin are coated on to a film base, glass or paper substrate.
The gelatin is a vital part of the emulsion as the protective
colloid of appropriate physical and chemical properties. Gelatin
may also contain trace elements (such as sulfur) which increase
the light sensitiv