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:

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.