To determine the correct electron configuration for sodium (Na), we need to understand atomic structure and electron arrangement.
Sodium (Na) has an atomic number of 11, indicating it has 11 protons and 11 electrons in a neutral atom. The electrons are arranged in various shells and subshells according to increasing energy levels.
Let's assign the electrons step-by-step:
1. First Shell (n=1):
- The first shell contains the 1s subshell, which can hold a maximum of 2 electrons:
[tex]\[ 1s^2 \][/tex]
2. Second Shell (n=2):
- The second shell contains the 2s and 2p subshells.
- The 2s subshell can hold a maximum of 2 electrons:
[tex]\[ 2s^2 \][/tex]
- The 2p subshell can hold a maximum of 6 electrons:
[tex]\[ 2p^6 \][/tex]
3. Third Shell (n=3):
- The third shell starts with the 3s subshell.
- Having placed 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 6 electrons in the 2p subshell, we have accounted for 10 electrons in total ([tex]\(2 + 2 + 6 = 10\)[/tex]).
- Sodium has 11 electrons, so one electron is left. This electron goes into the 3s subshell:
[tex]\[ 3s^1 \][/tex]
Combining all these subshells, the electron configuration for sodium (Na) is:
[tex]\[ 1s^2 2s^2 2p^6 3s^1 \][/tex]
Now let's match this configuration with the options provided:
1. Option 1: [tex]\(1 s^2 2 s^2 2 p^6 2 d^1\)[/tex]
- This is not correct. Sodium does not have electrons in the 2d subshell.
2. Option 2: [tex]\(1 s^2 2 s^2 2 p^6 3 s^1\)[/tex]
- This is correct and matches our step-by-step assignment.
3. Option 3: [tex]\(1 s^2 2 p^6 3 d^3\)[/tex]
- This is not correct for sodium. There are errors in the placement of electrons, particularly with the absence of 2s electrons and incorrect placement in the 3d subshell.
Conclusively, the correct electron configuration for sodium (Na) is:
[tex]\[ 1s^2 2s^2 2p^6 3s^1 \][/tex]
Therefore, the correct option is:
[tex]\[ \boxed{2} \][/tex]
