Year 9- Atoms and Ions


  • Atoms have a small central nucleus.
    • This is made up of protons and neutrons- it is also surrounded by electrons.
  • All of these structures inside the atom have relative electircal charges:
    • A Proton has a charge of +1
    • A Neutron has a charge of 0 (neutral)
    • An Electron has a charge of -1
  • In an atom the number of electrons is equal to the number of protons in the nucleus.
    • Therefore atoms have no overall charge.
  • The number of protons in an atom of an element is it's atomic number
  • The sum of the number of protons and neutrons in an atom is it's mass number
  • Each part of an atom has a relative mass:
    • A Proton has a relative mass


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