Atoms

• Definition of isotopes.

  Isotopes are atoms of an element with the same number of protons and electrons but different numbers of neutrons.
• Definition of relative isotopic mass.

  The mass of an atom of an isotope of an element relative to 1/12th the mass of an atom of carbon-12.
• Definition of relative atomic mass.

  The weighted average mass of an atom of an element relative to 1/12th the mass of an atom of carbon-12.
• What is the relative mass of a proton ?

  1
• What is the relative mass of a neutron ?

  1
• What is the relative mass of an electron ?

  1/1800
• What is the atomic number made up of ?

  protons
• What is the mass number made up of ?

  protons and neutrons