assuming that core electrons contribute 1.00 and valence electrons contribute nothing to the screening constant, S, calculate Zeff for Cl and K.
If I read this right, K = 19+ - 18 core = 1+ = Zeff.
Cl^- = 17+ - 18 = -1 = Zeff.
To calculate the effective nuclear charge (Zeff) for an atom, you need to determine the effective number of protons acting on the valence electrons. The effective nuclear charge can be obtained by subtracting the screening constant (S) from the actual atomic number (Z).
In this case, you are assuming that core electrons contribute 1.00 to the screening constant (S), and valence electrons contribute nothing. So, for both chlorine (Cl) and potassium (K), the valence electrons will experience the full nuclear charge.
Now, let's calculate Zeff for Cl and K:
1. Chlorine (Cl):
The atomic number of chlorine is 17. Chlorine has a configuration of 2, 8, 7, meaning there are two electrons in the first shell, eight electrons in the second shell, and seven valence electrons in the third shell.
Since the core electrons contribute 1.00 to the screening constant, and valence electrons contribute nothing, the screening constant (S) for chlorine is 1.00.
Thus, Zeff for chlorine can be calculated as:
Zeff (Cl) = Z (atomic number) - S (screening constant)
= 17 - 1.00
= 16.00
So, the effective nuclear charge (Zeff) for chlorine is 16.00.
2. Potassium (K):
The atomic number of potassium is 19. Potassium has a configuration of 2, 8, 8, 1, meaning there are two electrons in the first shell, eight electrons in the second shell, eight electrons in the third shell, and one valence electron in the fourth shell.
Since the core electrons contribute 1.00 to the screening constant, and valence electrons contribute nothing, the screening constant (S) for potassium is 1.00.
Thus, Zeff for potassium can be calculated as:
Zeff (K) = Z (atomic number) - S (screening constant)
= 19 - 1.00
= 18.00
So, the effective nuclear charge (Zeff) for potassium is 18.00.