the.com/electron shell
Where electrons live, rent-controlled by physics and never sharing a room wrong.
means An electron shell is one of the layered, fixed-energy zones around an atomic nucleus where electrons are allowed to exist, each shell holding only a limited number of them.
from From Latin 'electrum' (amber, where static electricity was first noticed by the Greeks rubbing it) plus Old English 'scell' (shell, husk, hard outer covering). 'Electron' was coined in the late 1800s for the unit of electric charge; 'shell' was borrowed afterward as a visual metaphor once physicists realized electrons cluster in concentric layers around the nucleus, like skins around an onion rather than planets in orbit — an image chemists kept because it was useful, even after quantum mechanics revealed the reality is fuzzier, more cloud than shell.
- capacity rule
- holds up to 2n squared electrons per shell
- outermost shell
- determines nearly all chemical behavior
- full shells
- make noble gases chemically antisocial
- not orbits
- probability clouds, not tiny planetary paths