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Inside an Atom
Age 14 · Chemistry
An atom has a tiny, heavy core called the nucleus, surrounded by electrons moving in shells at different distances. The nucleus holds protons and neutrons, while electrons fill the shells from the inside outward.
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In the picture
- Nucleus — the cluster of spheres at the center, holding almost all of the atom’s mass in a very small space.
- Proton — a crimson sphere inside the nucleus, carrying a positive charge.
- Neutron — a pearl-grey sphere inside the nucleus, carrying no charge at all.
- Inner shell — the small brass hoop closest to the nucleus, the first level electrons occupy.
- Electron — a blue bead riding the outer hoop, carrying a negative charge.
Examples
- A neon sign glows because electrons in the gas jump to a higher shell and give off light when they drop back down.
- The shock you feel touching a car door comes from outer-shell electrons rubbed from one surface onto another.
Key takeaways
- Nearly all the mass sits in the nucleus, but nearly all the volume is the electron shells.
- The outermost shell decides how an atom bonds with other atoms.
Quiz: Inside an Atom (Age 14)
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Where is almost all of an atom’s mass found?
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Which particle has no electric charge?
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When electrons fill an atom’s shells, which shell do they occupy first?
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