AQA Chemisty Atoms



Nucleus: 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 in the nucleus.

Electrons: Move around the nucleus in the electron shells (levels). They're negatively charged. Electrons have almost no mass.

Protrons are heavy (compared to electrons) and positively charged. Neutrons are heavy (compared to electrons) and neutral. Electrons are tiny and negatively charged.

Particle Relative Mass Relative Charged

Protons              1                      +1

Neutrons             1                        0

Electrons             Tiny                   -1

Atomic Number: Number of Protons



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