Question: how many valence electrons are in the following 1s22s22p63s23p64s23d104p5?
Answer: The electronic configuration of Bromine is 1s22s22p63s23p64s23d104p5 and the valence electrons are in the 4s and 4p orbitals giving Bromine 7 valence electrons. Elements whose atoms have the same number of valence electrons are grouped together in the Periodic Table of elements.