atomic structure and isotopes

• relative atomic mass = W1X1 + W2X2 + ..... / W1 + W2 + .....
• atoms consist of a central nucleus containing protons and neutrons
• the nucleus is small compared to the size of the whole atom
• the nucleus is surrounded by electrons in energy levels
• atoms have no electric charge because they contain the same number of protons and electrons
• proton:

  • relative mass = 1
  • relative charge = +1
• neutron:

  • relative mass = 1
  • relative charge = 0
• electron:

  • relative mass = 1/2000
  • relative charge = -1
• atomic number = number of protons and electrons
• mass number = number of protons and number of neutrons
• atoms of the same element have the same number of protons so its the number of protons that determines what type of atom it is
• isotopes are atoms with the same number of protons but different number of neutrons. this means they are atoms of the same element with the same atomic number but a different mass number