Question

the diagram shows the electron configuration around the chlorine nucleus. chlorine has 17 protons. which of the following correctly completes the statement? chlorine has ___ valence electrons, and the effective nuclear charge, z_eff, for the chlorine atom shown is ___. 7, 7- 7, 7+ 10, 7- 17, 7+

Explanation:

Step1: Determine valence electrons

Valence electrons are in the out - most shell. Chlorine has electron configuration 2, 8, 7. So it has 7 valence electrons.

Step2: Calculate effective nuclear charge

The formula for effective nuclear charge $Z_{eff}=Z - S$, where $Z$ is the atomic number (number of protons, $Z = 17$ for chlorine) and $S$ is the shielding constant. For the outermost electrons in chlorine, the inner electrons shield. There are 10 inner electrons. So $S = 10$, and $Z_{eff}=17 - 10=7$. The effective nuclear charge is a positive value as it represents the net positive charge attracting the outermost electrons. So $Z_{eff}=7+$.

Answer:

7, 7+