Question

In counting the electron pairs around the central atom in VSEPR theory, __________ are not included.

Answer 1

In VSEPR theory, nuclear-nuclear repulsions and nuclear-electron attractions are not included when counting electron pairs around the central atom. The theory only considers electron-pair repulsions to predict the arrangement of electron pairs and the correct arrangement of atoms in a molecule. Other interactions, such as nuclear-nuclear repulsions and nuclear-electron attractions, are involved in the final arrangement of atoms in a molecular structure.

Step-by-step explanation:

In counting the electron pairs around the central atom in VSEPR theory, nuclear-nuclear repulsions and nuclear-electron attractions are not included. The VSEPR model predicts the arrangement of electron pairs around each central atom based on the repulsion between electron pairs. It assumes that electron pairs in the valence shell of a central atom will adopt an arrangement that minimizes repulsions between them by maximizing the distance between them. However, other interactions such as nuclear-nuclear repulsions and nuclear-electron attractions also play a role in determining the final arrangement of atoms in a molecule.

Answer 2

See Explanation

Step-by-step explanation:

Electron pairs about the central element in simple binary compounds can be determined as follows:

Total e⁻ pairs = Bonded e⁻ pairs + Non-bonded e⁻ pairs

Example:

Given XeF₄ determine the total e⁻ pairs about the central element Xe.

Bonded e⁻ pairs = #substrates bonded to central element

= 4 Fluoride atoms

=> 4 Bonded e⁻ pairs

Non-bonded e⁻ pairs = [Valence# - Substrate#] / 2

Valence# = Xe + 4F = 1(8) + 4(7) = 36 valence e⁻s

Substrate# = 4F = 4(8) = 32 bonded e⁻s (about central element)

Non-bonded e⁻ pairs = V# - S# / 2 = 36 - 32 / 2 = 4/2 = 2 non-bonded pr.

Total e⁻ prs around central element = Bonded Pr e⁻ + Non-bonded e⁻

= 4 + 2 = 6 e⁻ pairs

This implies a Trigonal Bipyramidal parent geometry with a Square Planer molecular geometry.