Elements that have large negative electron affinities generally have (LO 6.10) (a) high values for Zeff and a vacancy in a valence orbital. (b) low values for Zeff and a vacancy in a valence orbital. (c) high values for Zeff and filled valence orbitals. (d) low values for Zeff and filled valence orbitals.

Verified step by step guidance

1. Understand that electron affinity refers to the energy change when an electron is added to a neutral atom in the gas phase, forming a negative ion.
2. Recognize that a large negative electron affinity means the atom releases a significant amount of energy when gaining an electron, indicating a strong attraction for the electron.
3. Recall that the effective nuclear charge (Z_eff) is the net positive charge experienced by an electron in a multi-electron atom, which affects the atom's ability to attract additional electrons.
4. Consider that a high Z_eff means the nucleus has a strong pull on the electrons, making it more likely for the atom to attract additional electrons and have a large negative electron affinity.
5. Evaluate the options: Atoms with high Z_eff and a vacancy in a valence orbital are more likely to have large negative electron affinities, as they can accommodate additional electrons easily.

Key Concepts

Electron Affinity

Electron affinity refers to the amount of energy released when an electron is added to a neutral atom in the gas phase. Elements with large negative electron affinities tend to readily accept electrons, indicating a strong attraction between the incoming electron and the nucleus. This property is crucial for understanding the reactivity of nonmetals, particularly halogens, which typically have high electron affinities.

Effective Nuclear Charge (Zeff)

Effective nuclear charge (Zeff) is the net positive charge experienced by an electron in a multi-electron atom. It accounts for the shielding effect of inner-shell electrons, which reduces the full nuclear charge felt by valence electrons. A high Zeff means that valence electrons are held more tightly by the nucleus, influencing an element's ability to attract additional electrons.

Valence Orbitals

Valence orbitals are the outermost orbitals of an atom that contain the valence electrons, which are involved in chemical bonding. The occupancy of these orbitals—whether they are filled or have vacancies—affects an atom's reactivity and its ability to gain or lose electrons. Elements with vacancies in their valence orbitals are generally more reactive, as they can easily accept additional electrons.