- It's in the middle of the atom
- It contains protons and neutrons
- It has a positive charge because of the protons.
- Almost the whole mass of the atom is concentrated in the nucleus
- But size-wize it's tiny compared to the rest of the atom
- Move around the nucleus
- They're negatively charged.
- They're tiny, but they cover a lot of space.
- The volume of their orbits determines how big the atom is.
- They have virtually no mass
- They're arranged in shells around the nucleus
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Atoms - Particles
- Protons are heavy and postively charged
- Neutrons are heavy and neutral
- Electrons are tiny and negatively charged
The number of Protons Equals number of Electrons
- Neutral atoms have no charged overall
- The charge on the electrons is the same as the charge on the protons - but opposite.
- This means the number f protons always equals the number of electrons in a neutral atom.
- If some electrons are added or removed, the atom becomes charged and is then an ion
- The number of neutrons isn't fixed but is usually about the same as the number of protons
Atoms of the same element all have the same number of protons - and atoms of different elements will have different numbers of protons.
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