This problem is asking for the theoretical effective nuclear charge for sodium and a reason behind its difference with the actual one. At the end, the answers are 1+ and because the 3s¹ electron has a small probability of being closer to the nucleus.
<h3>Effective nuclear charges</h3>
In chemistry, the effective nuclear charge is defined as the net positive charge valence electrons experience. In addition, one can approximate it with the equation:
Zeff = Z – S
Where Z is the atomic number or number of electrons and S the core electrons.
In such a way, since sodium has 11 electrons and 10 core electrons due to its electron configuration (1s²2s²2p⁶3s¹), one concludes its effective nuclear charge is:
Zeff = 11 - 10 = +1
On the other hand, since the actual effective nuclear charge has a value of about 2.667, one concludes this difference is due to the fact that the 3s¹ electron has a small tendency of being closer to the nucleus and therefore, there is a likelihood that this electron undergoes a greater attraction in comparison to the proposed in the theoretical model.
Learn more about effective nuclear charges: brainly.com/question/6965287