To determine the ion formed in the reaction between bromine and sodium, as well as whether bromine is oxidized or reduced, we need to understand the concept of oxidation and reduction.
Oxidation and reduction are terms used to describe the transfer of electrons between atoms or molecules. In a reaction, if an atom or ion loses electrons, it is oxidized, while if it gains electrons, it is reduced.
In the case of the reaction between bromine and sodium:
Bromine is a halogen element and its electron configuration is 1sĀ²2sĀ²2pā¶3sĀ²3pā¶4sĀ²3dĀ¹ā°4pāµ.
Sodium is an alkali metal and its electron configuration is 1sĀ²2sĀ²2pā¶3sĀ¹.
During the reaction, sodium donates its one valence electron (3sĀ¹) to bromine. This electron is transferred from sodium to bromine.
As a result, the bromine atom gains an electron and becomes an anion (a negatively charged ion). When bromine gains one electron, its electron configuration becomes 1sĀ²2sĀ²2pā¶3sĀ²3pā¶4sĀ²3dĀ¹ā°4pā¶, just like the noble gas krypton (Kr). Therefore, the bromine atom forms the bromide ion (Brā»).
Now let's determine whether bromine is oxidized or reduced:
Since the bromine atom gains an electron, it has a reduction in its oxidation state (the number of electrons lost or gained). In its elemental form, bromine has an oxidation state of 0. However, when it forms the bromide ion (Brā») by gaining an electron, its oxidation state decreases from 0 to -1. This reduction in the oxidation state indicates that bromine is reduced.
In summary, the reaction between bromine and sodium forms the bromide ion (Brā»), and bromine is reduced.