What is the effective nuclear charge (Z_{eff}) experienced by a valence electron in an oxygen atom?

• A. Z_{eff} = 8 - 8 = 0
• B. Z_{eff} = 8 - 6 = 2
• C. Z_{eff} = 8 - 4 = 4
• D. Z_{eff} = 8 - 2 = 6

Answer: (C)

Verified step by step guidance

1. Identify the atomic number (Z) of oxygen, which is 8. This represents the total number of protons in the nucleus and the total positive charge attracting the electrons.
2. Understand that the effective nuclear charge (Z_{eff}) is the net positive charge experienced by an electron after accounting for the shielding effect of other electrons.
3. Determine the number of shielding (or screening) electrons. For a valence electron in oxygen, the inner core electrons (those in the 1s orbital) primarily shield the valence electrons. Oxygen has 2 core electrons in the 1s orbital.
4. Apply Slater's rules or a simplified approach to estimate the shielding constant (S). For valence electrons in oxygen, the core electrons contribute most to shielding, so S is approximately equal to the number of core electrons, which is 2.
5. Calculate the effective nuclear charge using the formula: \(Z_{eff} = Z - S\), where \(Z\) is the atomic number and \(S\) is the shielding constant. Substitute the values to find \(Z_{eff} = 8 - 2\).