atom and elements

• Relative atomic mass

  Mass number
• relative atomic mass/ mass number

  protons + neutrons
• Atomic number 


  number of protons
• Number of neutrons

  mass number - atomic number
• proton

  charge: +1
• electron

  charge: -1
• neutron

  charge: 0
• proton

  found in the nucleus
• electron

  found in the electron shells
• neutron

  found in the nucleus
• number of electrons = number of protons
• the total mass of an element is equal to the sum of its protons and neutrons.