Describe the structure of sodium metal?

The body-centred cubic (bcc) structure is the most stable form for sodium metal at 298 K (25°C). Under normal conditions, all of the Group 1 (alakali metals) elements are based upon the bcc structure. The closest Na-Na separation is 372 pm implying a sodium metallic radius of 186 pm.

Explanation:

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.