To determine the correct electron configuration for bromine (Br), which has an atomic number of 35, we can follow the Aufbau principle. This principle states that electrons fill orbitals starting from the lowest energy level to the highest.
Here are the detailed steps to find the electron configuration for bromine:
1. Start with the lowest energy level, which is the 1s orbital.
- The 1s orbital can hold 2 electrons.
- Configuration so far: [tex]\( 1s^2 \)[/tex]
2. Next is the 2s orbital.
- The 2s orbital can hold 2 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 \)[/tex]
3. Next are the 2p orbitals.
- The 2p orbitals can collectively hold 6 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 \)[/tex]
4. Next is the 3s orbital.
- The 3s orbital can hold 2 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 3s^2 \)[/tex]
5. Next are the 3p orbitals.
- The 3p orbitals can collectively hold 6 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 3s^2 3p^6 \)[/tex]
6. Next is the 4s orbital.
- The 4s orbital can hold 2 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 \)[/tex]
7. Next are the 3d orbitals.
- The 3d orbitals can collectively hold 10 electrons.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} \)[/tex]
8. Finally, the electrons will fill the 4p orbitals.
- Bromine has 35 electrons, so the remaining 5 electrons will go into the 4p orbitals.
- Configuration so far: [tex]\( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5 \)[/tex]
Thus, the electron configuration for bromine (Br) is:
[tex]\[ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5 \][/tex]
From the given options, the correct one is:
[tex]\[ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5 \][/tex]
Therefore, the correct answer is option 1.
