Question: what is the electron configuration for p3-?
Answer: P3–: From Table 2.2, the electron configuration for an atom of phosphorus is 1s22s22p63s23p3. In order to become an ion with a minus three charge, it must acquire three electrons—in this case another three 3p. Thus, the electron configuration for a P3– ion is 1s22s22p63s23p6.