Silver bromide (AgBr), a soft, pale-yellow, water-insoluble salt well known (along with other silver halides) for its unusual sensitivity to light. This property has allowed silver halides to become the basis of modern photographic materials. AgBr is widely used in photographic films and is believed by some to have been used for making the Shroud of Turin. The salt can be found naturally as the mineral bromargyrite (bromyrite).

Although the compound can be found in mineral form, AgBr is typically prepared by the reaction of silver nitrate with an alkali bromide, typically potassium bromide:

Although less convenient, the salt can also be prepared directly from its elements.

Modern preparation of a simple, light-sensitive surface involves forming an emulsion of silver halide crystals in a gelatine, which is then coated onto a film or other support. The crystals are formed by precipitation in a controlled environment to produce small, uniform crystals (typically < 1 μm in diameter and containing ~10¹² Ag atoms) called grains.

Silver bromide reacts readily with liquid ammonia to generate a variety of amine complexes:

AgBr + nNH₃ → Ag(NH₃)₂¹⁺

Silver bromide reacts with triphenylphosphine to give a tris(triphenylphosphine) product:

AgF, AgCl, and AgBr all have face-centered cubic (fcc) rock-salt (NaCl) lattice structure with the following lattice parameters:

The larger halide ions are arranged in a cubic close-packing, while the smaller silver ions fill the octahedral gaps between them, giving a 6-coordinate structure where a silver ion Ag⁺ is surrounded by 6 Br⁻ ions, and vice versa. The coordination geometry for AgBr in the NaCl structure is unexpected for Ag(I) which typically forms linear, trigonal (3-coordinated Ag) or tetrahedral (4-coordinated Ag) complexes.

Unlike the other silver halides, iodargyrite (AgI) contains a hexagonal zincite lattice structure.

The silver halides have a wide range of solubilities. The solubility of AgF is about 6 × 10⁷ times that of AgI. These differences are attributed to the relative solvation enthalpies of the halide ions; the enthalpy of solvation of fluoride is anomalously large.

Although photographic processes have been in development since the mid-1800s, there were no suitable theoretical explanations until 1938 with the publication of a paper by R.W. Gurney and N.F. Mott. This paper triggered a large amount of research in fields of solid-state chemistry and physics, as well more specifically in silver halide photosensitivity phenomena.

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