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Understanding protons, neutrons, electrons, and shells
The nucleus has protons (+) and electrons (−) orbit around it. Opposite charges attract — so why don't electrons crash into the nucleus?
Quantum mechanics: Electrons exist in specific energy levels (shells). They can't spiral inward because there's no energy level below the lowest shell.
Select different elements above to see their electron configurations.
Test your understanding of atoms and electrons
Sodium (Na) has electron configuration 2-8-1. In chemical reactions, sodium tends to: