Editing Bromine (section)

===Other binary bromides===
[[File:Bromid stříbrný.PNG|thumb|right|[[Silver bromide]] (AgBr)]]
Nearly all elements in the periodic table form binary bromides. The exceptions are decidedly in the minority and stem in each case from one of three causes: extreme inertness and reluctance to participate in chemical reactions (the [[noble gas]]es, with the exception of [[xenon]] in the very unstable [[Xenon dibromide|XeBr{{sub|2}}]]); extreme nuclear instability hampering chemical investigation before decay and transmutation (many of the heaviest elements beyond [[bismuth]]); and having an electronegativity higher than bromine's ([[oxygen]], [[nitrogen]], [[fluorine]], and [[chlorine]]), so that the resultant binary compounds are formally not bromides but rather oxides, nitrides, fluorides, or chlorides of bromine. (Nonetheless, [[nitrogen tribromide]] is named as a bromide as it is analogous to the other nitrogen trihalides.)<ref name="Greenwood821">Greenwood and Earnshaw, pp. 821–4</ref>

Bromination of metals with Br{{sub|2}} tends to yield lower oxidation states than chlorination with Cl{{sub|2}} when a variety of oxidation states is available. Bromides can be made by reaction of an element or its oxide, hydroxide, or carbonate with hydrobromic acid, and then dehydrated by mildly high temperatures combined with either low pressure or anhydrous hydrogen bromide gas. These methods work best when the bromide product is stable to hydrolysis; otherwise, the possibilities include high-temperature oxidative bromination of the element with bromine or hydrogen bromide, high-temperature bromination of a metal oxide or other halide by bromine, a volatile metal bromide, [[carbon tetrabromide]], or an organic bromide. For example, [[niobium(V) oxide]] reacts with carbon tetrabromide at 370&nbsp;°C to form [[niobium(V) bromide]].<ref name="Greenwood821" /> Another method is halogen exchange in the presence of excess "halogenating reagent", for example:<ref name="Greenwood821" />
:FeCl{{sub|3}} + BBr{{sub|3}} (excess) → FeBr{{sub|3}} + BCl{{sub|3}}
When a lower bromide is wanted, either a higher halide may be reduced using hydrogen or a metal as a reducing agent, or thermal decomposition or [[disproportionation]] may be used, as follows:<ref name="Greenwood821" />
: 3 WBr{{sub|5}} + Al {{overunderset|→|thermal gradient|475&nbsp;°C → 240&nbsp;°C}} 3 WBr{{sub|4}} + AlBr{{sub|3}}
: EuBr{{sub|3}} + {{sfrac|1|2}} H{{sub|2}} → EuBr{{sub|2}} + HBr
: 2 TaBr{{sub|4}} {{overunderset|→|500&nbsp;°C|&nbsp;}} TaBr{{sub|3}} + TaBr{{sub|5}}

Most metal bromides with the metal in low oxidation states (+1 to +3) are ionic. Nonmetals tend to form covalent molecular bromides, as do metals in high oxidation states from +3 and above. Both ionic and covalent bromides are known for metals in oxidation state +3 (e.g. [[scandium bromide]] is mostly ionic, but [[aluminium bromide]] is not). [[Silver bromide]] is very insoluble in water and is thus often used as a qualitative test for bromine.<ref name="Greenwood821" />