Atoms

  • Radius of 1×10^-10m

  • Nucleus contains protons and neutrons, radius of 1×10^-14m, almost whole mass of atom is in nucleus

  • Electrons move around nucleus on shells, 1st shell holds max 2ē, 2nd and 3rd hold max 8ē, 4th holds max 18

  • Same number of proton and electron

  • In an ion the number of protons isn’t equal to number of electron

  • On periodic table , top number - mass number (total number of protons AND neutrons) bottom number - atomic number (number of protons)

  • Mass:

    • Proton- 1

    • Neutron- 1

    • Electron- very small