Structure of Atoms

• Protons - in the nucleus - +1

  Neutrons - in the nucleus - 0

  Electrons - orbiting the nucleus - -1
• Atomic number


  Number of protons - atomic number also tells you the number of electrons in the atom
• Mass number 


  The mass number is the number of protons and electrons added together to make the number of nucleons
• Isotopes

  Isotopes are atoms with a different number of protons but same number of neutrons