Which of the following is NOT a property affected by the effective nuclear charge, Zeff?

• A. Atomic radius
• B. Ionization energy
• C. Molar mass
• D. Electronegativity

Answer: (C)

Verified step by step guidance

1. Understand that the effective nuclear charge, \(Z_{eff}\), is the net positive charge experienced by an electron in a multi-electron atom. It influences how strongly electrons are attracted to the nucleus.
2. Recognize that properties like atomic radius, ionization energy, and electronegativity are directly affected by \(Z_{eff}\) because they depend on the attraction between the nucleus and the electrons.
3. Atomic radius decreases as \(Z_{eff}\) increases because electrons are pulled closer to the nucleus.
4. Ionization energy increases with higher \(Z_{eff}\) since more energy is required to remove an electron that is held more tightly.
5. Electronegativity also increases with \(Z_{eff}\) because atoms with a higher effective nuclear charge attract bonding electrons more strongly.
6. Molar mass, however, is a property related to the mass of atoms or molecules and depends on the number and type of atoms, not on the effective nuclear charge. Therefore, molar mass is NOT affected by \(Z_{eff}\).