Valence electrons
Definition
The electrons in an atom’s outermost shell, the only electrons that take part in bonding and reactions.
Electrons fill shells from the inside out, each shell sitting farther from the nucleus at higher energy. Inner-shell electrons are buried and shielded, so only the outermost shell touches the outside world. Atoms bond, share, steal, or surrender these valence electrons to reach a filled outer shell, which is the engine of chemistry. Elements in the same periodic group share valence counts and therefore share chemistry.
Related concepts
Electron · Bonding · Electron shells
How it connects
Part of The Blueprint of Water · 🧪 chemistry