A) Radium-223 can be displayed as `^223 Ra` or Ra-223.
B) An alpha-particle is a Helium nucleus, i.e. it is two protons and two neutrons. If the Radium loses two protons it's atomic number goes down by 2 from 88 to 86. Element 86 on the Periodic Table is Radon, chemical symbol Rn. The atomic mass of an element is the combined number of protons and neutrons in the nucleus of one atom. Since the alpha particle contains 2 protons and 2 neutrons the product of the radioactive decay will have an atomic mass 4-less than the parent isotope. 223-4=219. The product is `^219Rn` or Rn-219, and an alpha-particle, which takes two electrons from the first thing it contacts to become a Helium atom.