What is the correct formula for silver bromide?
a. SiBr
b. AgBr
c. SiBr2
d. AgBr3
The correct answer and explanation is:
The correct formula for silver bromide is b. AgBr.
Silver bromide is a chemical compound made up of silver (Ag) and bromine (Br). To understand why the formula is AgBr, it is important to look at the properties and typical charges of the ions involved.
Silver is a metal and commonly forms a +1 charge in ionic compounds. This means silver tends to lose one electron to form a silver ion, Ag⁺. Bromine, on the other hand, is a halogen and typically gains one electron to form a bromide ion, Br⁻, which has a -1 charge.
Because the positive charge of the silver ion (+1) balances the negative charge of the bromide ion (-1), only one atom of silver is needed for every bromide ion to create a neutral compound. Therefore, the formula must reflect a 1:1 ratio of silver to bromide ions, resulting in AgBr.
Looking at the other options:
- SiBr and SiBr₂ involve silicon (Si), which is not part of silver bromide. Silicon is a metalloid and does not form this compound.
- AgBr₃ implies three bromide ions for every silver ion. This would create an imbalance in charges since silver usually only has a +1 charge, and bromide has a -1 charge. Therefore, this formula is incorrect for silver bromide.
Silver bromide is widely used in photographic films and papers because it is sensitive to light. When exposed to light, it decomposes, producing elemental silver and bromine, which creates the image on photographic materials.
In summary, the correct formula AgBr represents one silver ion and one bromide ion combined in equal proportions, resulting in a neutral compound. This matches the chemical behavior and ionic charges of silver and bromine, making option b. AgBr the correct choice.