Each yellow and orange (barred to distinguish) dot gets a letter.
The center green dot does not get a letter.
The final answer is a relevant word, once you unscramble it.
The final answer is:
We know that we need to enter letters into each circle (except the green one) in this diagram which resembles very much a diagram of electron shells:
So what should we try to enter here? Well, of note here is that we appear to have 12 words spelled out from the centre to the outermost edge, sharing letters with neighbouring words where required. And since we have a chemistry theme, it isn't too far to leap (if you have the knowledge) to attempting to fit...
...the names of 12 elements that begin with the same letter. And there's only one letter which starts the name of 12 chemical elements: C. Those elements being CADMIUM, CAESIUM, CALCIUM, CALIFORNIUM, CARBON, CERIUM, CHLORINE, CHROMIUM, COBALT, COPERNICIUM, COPPER, and CURIUM.
Counting up the number of letters in these and the number of letters in the words radiating out from the centre of the diagram, I realised this was a perfect match, as long as 'CAESIUM' was spelled with the 'A' that is often omitted in US English.
If we do this, we end up with the resulting filled diagram:
My order of completion:
1. CAESIUM (only 7 letter word using the pre-filled 'E' in the third position - also confirmed the need for using the 'AE' variant spelling).
2. CALCIUM/CALIFORNIUM due to the shared first 3 letters.
3. CADMIUM - the only remaining 7-letter element on the list.
4. COPPER/COPERNICUM (the other long word on the list).
5. COBALT, using the 'CO' beginning.
6. CERIUM/CURIUM - two words differing by a single letter.
7. CARBON - the remaining 6-letter element.
8. CHROMIUM/CHLORINE, positioned so that 'CHLORINE' shared the 5th-position 'R' with 'COPERNICUM'.
Finally, look at the 8 letters in orange. These anagram to:
ELECTRON, a very appropriate word given the theme of the puzzle.