We found 11 dictionaries that define the word valence electrons:

General (5 matching dictionaries)

1. valence electrons: Merriam-Webster
2. valence electrons: Wiktionary
3. valence electrons: The Wordsmyth English Dictionary-Thesaurus
4. valence electrons: Dictionary.com
5. Valence electrons: Wikipedia, the Free Encyclopedia

Computing (1 matching dictionary)

6. Valence electrons: Encyclopedia

Medicine (2 matching dictionaries)

7. valence electrons: Merriam-Webster Medical Dictionary
8. Valence electrons: Medical dictionary

Science (3 matching dictionaries)

9. Chemistry Dictionary (No longer online)
10. valence electrons: UNCChem Glossary
11. Atmospheric Chemistry and Air Quality (No longer online)

(Note: See valence_electron as well.)

Definitions from Wiktionary (valence electron) ▸ noun:  (chemistry) Any of the electrons in the outermost shell of an atom (the valence shell); capable of forming bonds with other atoms. ▸ Also see valence_electron Opposite: core electrons ▸ Words similar to valence electrons ▸ Usage examples for valence electrons ▸ Idioms related to valence electrons ▸ Wikipedia articles (New!) ▸ Words that often appear near valence electrons ▸ Rhymes of valence electrons ▸ Invented words related to valence electrons