How do colors arise when you look at it on an atomic scale?

Answer

Dear Cees,

Color is caused by an interaction between light on the one hand and electrons on the other and the color is then a reflection of the possible energy states in which these electrons can be.

Where do you find electrons? In the first place in atoms (as you indicate) but also in molecules (are actually quite stable collections of atoms held together by chemical bonds).

There are roughly 100 of the atoms and should be regarded as basic building blocks. The number of molecules is endless as there is no limit on combining atoms into molecules. Certainly organic molecules that are mainly made up of carbon and hydrogen atoms (and a few kinds of other atoms in smaller relative amounts) come in an infinite number of variants. Recently, the 50,000,000th synthetic organic molecule has been made. In addition, there are certainly so many connections that nature makes. Indeed living matter consists mainly of organic compounds. Certainly every living being contains thousands of different compounds, some of which have very specific properties, eg as a dye.

Red, yellow, green or orange peppers do not differ that much from each other, but they do differ in the dye they contain in their skins and cells. That dye is responsible for the color and since they are different substances or occur in different proportions, you have peppers in different colors. So to come back to your question, it is indeed true that the atomic composition of the different peppers is the same, but they differ in the molecules that are present and that can be built with the same atoms. More specifically, this applies especially to the dye molecules.

Regards