Molecular Geometry and VSEPR Theory

What is the primary purpose of the VSEPR theory?

• To determine the electronegativity of atoms.

• To predict the shape and geometry of covalent molecules.

• To calculate the bond energy of chemical bonds.

• To identify the type of chemical bonding in a molecule.

How is the central atom in a molecule typically identified for VSEPR analysis?

• It is always the atom with the highest atomic mass.

• It is the least electronegative element in the molecule, unless it is hydrogen.

• It is the atom that forms the most single bonds.

• It is the atom located at the center of the periodic table.

What factors determine the shape of a molecule according to VSEPR theory?

• The atomic number and mass of the central atom.

• The number and nature of electron pairs in the valence shell of the central atom.

• The ionization energy and electron affinity of the atoms.

• The presence of metallic or ionic bonds.

What is the correct order of repulsion strength between different types of electron pairs?

• Lone pair-lone pair > Lone pair-bond pair > Bond pair-bond pair

• Bond pair-bond pair > Lone pair-bond pair > Lone pair-lone pair

• Lone pair-bond pair > Bond pair-bond pair > Lone pair-lone pair

• Bond pair-bond pair > Lone pair-lone pair > Lone pair-bond pair

What is the correct order of repulsion between electron pairs?

• LP-LP > LP-BP > BP-BP

• BP-BP > LP-BP > LP-LP

• LP-BP > LP-LP > BP-BP

• BP-BP > LP-LP > LP-BP

A molecule with two bond pairs and no lone pairs will exhibit what molecular geometry and bond angle?

• Trigonal planar, 120°

• Linear, 180°

• Bent, <120°

• Tetrahedral, 109.5°

What is the molecular geometry and bond angle for a molecule with three bond pairs and no lone pairs?

• Tetrahedral, 109.5°

• Linear, 180°

• Trigonal planar, 120°

• Trigonal pyramidal, 107°

If a molecule has two bond pairs and one lone pair, what will be its molecular geometry and how will its bond angle compare to the ideal trigonal planar angle?

• Trigonal pyramidal, greater than 120°

• Bent, less than 120°

• Linear, equal to 180°

• Tetrahedral, equal to 109.5°

Why does phosphorus pentachloride (PCl5) readily dissociate into phosphorus trichloride (PCl3) and chlorine gas (Cl2)?

• The equatorial bonds are weaker and longer than the axial bonds.

• The axial bonds are weaker and longer than the equatorial bonds.

• PCl5 is an unstable molecule due to high electronegativity of phosphorus.

• The bond angles in PCl5 are all 90 degrees, leading to high repulsion.

What is the molecular geometry of sulfur tetrafluoride (SF4) and what are its approximate bond angles?

• Trigonal bipyramidal; 90° and 120°

• Seesaw; <90° and <120°

• Tetrahedral; 109.5°

• Square planar; 90°