Neon varieties

Thomson studied how positively charged subatomic particles were deflected by magnetic and electric fields and where they landed on a photographic plate. He discovered two varieties of neon atoms differing in charge, mass, or both, foreshadowing new concepts of atomic structure.
 Joseph John Thomson England 1912 Neon varieties

Thomson studied how positively charged subatomic particles were deflected by magnetic and electric fields and where they landed on a photographic plate. He discovered two varieties of neon atoms differing in charge, mass, or both, foreshadowing new concepts of atomic structure.