how many core electrons are there in?

Question

Z=47 and Z=86

Answer 1

Z = 47 has 45 core electrons (2 valence e-)
Silver transfers one of its valence e- to an inner "d" level to leave only one valence e- and thus has a charge of 1+ when reacting.

Z = 86 has 78 core electrons (8 valence e-)
Radon is a noble gas and has a full octect of valence electrons. The remainder of the electrons must be core e-.