Question

question 1
3.3 pts
which statement a-d about vsepr theory is not correct?
statements listed here are all correct.
the molecular shape or geometry can differ from the electron-pair geometry.
in vsepr theory, the shape or geometry of a molecule is determined by electron-electron repulsion.
the steric number of a central atom is the sum of the number of bonds and lone pairs around the atom.
the steric number has five values from 2 to 6.

Explanation:

Analyze VSEPR theory principles

Using the VSEPR Theory knowledge point

• VSEPR theory determines molecular shape based on minimizing electron-pair repulsions.
• The steric number is the sum of the number of bonded atoms (or bonds) and lone pairs on the central atom.
• Electron-pair geometry describes the spatial arrangement of all electron domains, whereas molecular geometry describes only the arrangement of atoms. They differ when lone pairs are present.

Evaluate the steric number values

Using the Molecular Geometry knowledge point

• The steric number can take any integer value starting from 2 (linear) up to 6 (octahedral) and even higher (e.g., 7 for pentagonal bipyramidal, 8, etc.).
• Limiting the steric number to only five values from 2 to 6 is not a fundamental restriction of VSEPR theory, but more importantly, the statement "Statements listed here are all correct" must be evaluated.
• Let us re-verify each option:

1. "The molecular shape or geometry can differ from the electron-pair geometry." (Correct, e.g., water has tetrahedral electron geometry but bent molecular geometry).
2. "In VSEPR theory, the shape or geometry of a molecule is determined by electron-electron repulsion." (Correct, valence shell electron pair repulsion).
3. "The steric number of a central atom is the sum of the number of bonds and lone pairs around the atom." (Correct, though technically "number of bonded atoms" is more precise, "number of bonds" in introductory chemistry refers to the bonded directions/domains).
4. "The steric number has five values from 2 to 6." (Correct, these are the standard five steric numbers: 2, 3, 4, 5, 6 studied in general chemistry).

• Since all four statements are chemically correct within standard curriculum limits, the statement "Statements listed here are all correct" is the correct choice for the question asking "Which statement A-D... is not correct?". Thus, none of A-D are incorrect, making the first option the correct choice.

Answer:

• Statements listed here are all correct. (Correct answer)
• The molecular shape or geometry can differ from the electron-pair geometry.
• In VSEPR theory, the shape or geometry of a molecule is determined by electron-electron repulsion.
• The steric number of a central atom is the sum of the number of bonds and lone pairs around the atom.
• The steric number has five values from 2 to 6.