Sub atomic particles

• Atoms are made up of protons, neutrons and electrons.
• proton - positive charge
• electron - negative charge
• neutron - neither positive nor negative
• Larger number - atomic mass

  Smaller number - atomic number

  
• Atomic mass number = number of protons + number of neutrons
• Atomic number = number of protons
• Number of protons = number of electrons
• Isotopes are atoms that have the same atomic number but different mass numbers . They have the same number of protons and electrons but different number of neutrons. E.g. carbon 14 is the isotope of carbon with a mass number of 14
• Relative atomic mass - the average mass of an atom of an element
• Example question for relative atomic mass:

  75% of the chlorine in existence is Cl-35

  25% of the chlorine in existence is Cl-37

  35.5

  (75 x 35) + ( 25x 37 ) = 3555 / the two percentages ( 100 ) = 35.5