Sub-Atomic Particles

• All matter is made up of particles called Atoms.
• There are 3 sub-atomic particles:

  • Electrons,
  • Protons,
  • And, Neutrons
• The Nucleus of an atom is comprised of Protons and Neutrons. Surrounding the Nucleus is Electron Shells/Layers which hold Electrons.
• The Mass Number of an atom is the total number of protons and neutrons inside the Nucleus.
• The Atomic Number of an atom tells us how many protons are within the Nucleus.
• Atoms are neutral because the collective charges of the 3 subatomic particles are equal to 0:

  • Protons - +1
  • Electrons - -1
  • Neutrons 0
• The innermost electron shell can only hold 2 electrons, so the outermost shell can hold up to 8 electrons.