Question

In the reaction between bromine and sodium, a bromine atom gains an electron. What ion is formed? Is the bromine oxidized. or is it reduced?

Answer 1

Answer: $Br^-$ , It is reduced.

Explanation:

Electronic configuration of sodium:

$[Na]=1s^22s^22p^63s^1$

Sodium atom will loose one electron to gain noble gas configuration and form sodium cation with +1 charge.

$[Na^+]=1s^22s^22p^63s^0$

Electronic configuration of bromine:

$[Br]:35:[Ar]3d^{10}4s^24p^5$

Bromine atom will gain one electron to gain noble gas configuration and form bromide ion with -1 charge.

$[Br^-]:36:[Ar]3d^{10}4s^24p^6$

Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.

Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance decreases.

$Br+e^-\rightarrow Br^-$

Answer 2

When bromine gains an  electron it forms Br^- ion and Bromine is reduced coz it gained an electron