There are 86 protons in the radon nucleus. You determine this by looking for Rn in the periodic table and reading the atomic number for Rn. There are 86 electrons in a neutral radon atom because the 86 positive protons must have 86 negative electrons to bring the total charge to zero.
Copper has two naturally occurring isotopes.
Use the percent abundances and masses given here. Locate the following on the outline of a periodic table. Write the electron configuration for an atom with 17 electrons. Mark the valence electrons. Chlorine, Cl, is an atom with 17 electrons.