Structure of the atom
An atom has a tiny nucleus of protons and neutrons, with electrons orbiting around it. Protons are positive, electrons negative and neutrons neutral.
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Analogy
A tiny marble (nucleus) in the middle of a huge stadium, with electrons in the stands.
Example
Proton: +1Neutron: 0Electron: -1A neutral atom has equalprotons and electrons.
In practice
An atom is mostly empty space. Its size is about 0.0000000001 m across.
Practice
Flashcards
- What particles are in the nucleus?Protons and neutrons.
Questions people ask
Why are atoms neutral overall?
A normal atom has the same number of protons as electrons. Each proton carries +1 charge and each electron -1, so the charges cancel exactly. If an atom gains or loses electrons it becomes charged and is called an ion.
Where is most of an atom's mass?
Almost all of an atom's mass is in the nucleus. Protons and neutrons are each about 1,800 times heavier than an electron. The nucleus is tiny compared with the whole atom, so the atom is mostly empty space with a very dense centre.