Question: how many electrons are in the valence shell of phosphorus?
Answer: 1, how many valence electrons and how many core electrons does a neutral phosphorus atom have? The highest-numbered shell is the third shell, which has 2 electrons in the 3s subshell and 3 electrons in the 3p subshell. That gives a total of 5 electrons, so neutral phosphorus atoms have 5 valence electrons.