Question

How many electrons are there in `Br^-`?

Answer 1

The `"Br"^(-)"` ion has 36 electrons.

Explanation:

The atomic number for bromine is 35, which means it has 35 protons in its atomic nuclei. A neutral bromine atom would also have 35 electrons. In order for a bromine atom to become a `1-` bromide ion, it would have to gain an additional electron.

Below is the Lewis dot structure for a neutral bromine atom, which has seven valence electrons.
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Below is the Lewis dot structure for a `"Br"^(-)"` ion, which has eight valence electrons. The extra valence electron gives it a negative charge.
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The diagram below shows how a bromine atom gains an electron from the element lithium in order to form the ionic compound LiBr.