Which of the following is closest to the effective nuclear charge (Z_ext{eff}) experienced by the valence electrons in a chlorine (Cl) atom?

• A. Z_ext{eff} ext{ for Cl} ext{ is approximately } 7
• B. Z_ext{eff} ext{ for Cl} ext{ is approximately } 11
• C. Z_ext{eff} ext{ for Cl} ext{ is approximately } 17
• D. Z_ext{eff} ext{ for Cl} ext{ is approximately } 1

Answer: (A)

Verified step by step guidance

1. Identify the atomic number (Z) of chlorine (Cl). Chlorine has an atomic number of 17, meaning it has 17 protons in its nucleus.
2. Understand that the effective nuclear charge (Z_{\text{eff}}) is the net positive charge experienced by valence electrons after accounting for the shielding effect of inner electrons.
3. Use Slater's rules or a simplified approach to estimate the shielding constant (S). For chlorine, the inner electrons (those not in the valence shell) shield the valence electrons from the full nuclear charge.
4. Calculate the effective nuclear charge using the formula: \(Z_{\text{eff}} = Z - S\), where \(Z\) is the atomic number and \(S\) is the shielding constant.
5. Estimate the value of \(S\) by counting the number of core electrons (usually the electrons in inner shells) and subtract this from \(Z\) to find \(Z_{\text{eff}}\) for the valence electrons.