Here's how to determine the second quantum number (azimuthal quantum number, l) for a 3p³ electron in phosphorus:

* Principal Quantum Number (n): The first number in the electron configuration (3) tells us the principal quantum number, which is 3.

* Azimuthal Quantum Number (l): The letter (p) indicates the subshell. Here's the relationship between subshells and l values:

* s = 0

* p = 1

* d = 2

* f = 3

Therefore, the second quantum number (l) for a 3p³ electron is 1.