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Atoms
Everything you can touch is built from atoms — a tiny dense nucleus and a cloud of electrons. Change the count and you change the element.
Atom builder
Add or remove protons. Watch electrons fill the shells.
Protons6
Element
Carbon
Shells
2 · 4
Outer
4 e⁻
Shells fill 2, 8, 8, 18…
Inside an atom
- Protons — positive, in the nucleus. The number defines the element.
- Neutrons — neutral, in the nucleus. Different counts give isotopes.
- Electrons — negative, in shells around the nucleus.
The shell rule
Electrons fill the inner shells first. Capacities are 2, 8, 8, 18… That pattern is what makes the periodic table look the way it does — rows for shells, columns for outer-shell counts.
Why the outer shell decides chemistry
Atoms react by sharing or trading their outer electrons. Sodium (1 outer) gives one up; chlorine (7 outer) takes it. Result: table salt. Atoms with full outer shells (helium, neon, argon) are happy and rarely react.
The cloud, not the orbit
The orbit picture in the simulation is a useful cartoon. Reality is stranger — electrons live as fuzzy probability clouds called orbitals (s, p, d, f). That story belongs to quantum mechanics.