We are unable to see any list? Can you provide one?
A compound is a substance composed of 2 or more chemical elements.
The model does not represent a compound because it shows two atoms of the same element combined. To be a compound the model would need to contain atoms of different element, represented by different colored balls. Therefore, the picture does not represent a compound. :)
Explanation:
<h2>The number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital.</h2>