1. Electronic Configuration of Bromine
Bromine (Br) has an atomic number of 35, so its electronic configuration is:
* 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
2. Identify the Relevant Sublevel
We're interested in the third quantum number, which is the *magnetic quantum number* (ml). This number describes the orientation of an orbital in space within a given sublevel.
Bromine's outermost electrons reside in the 4p sublevel.
3. Understanding Magnetic Quantum Numbers (ml)
* The p sublevel has three orbitals, each with a different spatial orientation.
* The values of ml for a p sublevel are: -1, 0, +1.
4. Third Quantum Number
Since we want the third quantum number for *one* of the electrons in the 4p sublevel, any of the following would be correct:
* ml = -1
* ml = 0
* ml = +1
In Conclusion
The third quantum number (ml) for an electron in the 4p sublevel of bromine can be either -1, 0, or +1.
