An ion source produces a beam containing ions R and S. The ions are formed from different isotopes of the same element.
| Ion | Information |
|---|---|
| R | contains 14 electrons and 20 neutrons; formed when three electrons were removed from a neutral atom |
| S | has mass number 39 and relative charge +2 |
Calculate the number of electrons and the number of neutrons in ion S.
Compare the approximate masses of ions R and S. Ignore the mass of the electrons.