Why are the spheres representing nitrogen and oxygen different colors?

1 Answer
Nov 5, 2016

Answer:

It's for the students to tell them apart.

Explanation:

Of course atoms don't have different colours. But in a model (=visual representation of what you think is happening) you will want to show how for instance a molecule is built up from different atoms.
A difference in size also helps (as between hydrogen and oxygen), but only if sizes are very different.