VSEPR Practice

VSEPR stands for ________ theory.

• Valence Structure of Electron Pyramids and Regression

• Varied Structures of Electrons Paired and Replaced

• Varied Shell Energy of Protons and Radiation

• Valence Shell Electron Pair Repulsion

Answer explanation

VSEPR stands for Valence Shell Electron Pair Repulsion, which is a theory used to predict the geometry of molecules based on the repulsion between electron pairs in the valence shell of atoms.

According to VSEPR, molecules adjust their shapes to keep which of the following as far away as possible?

• Pairs of valence electrons

• Inner shell electrons

• Mobile Electrons

• Electrons closest to the nucleus

Answer explanation

According to VSEPR theory, molecules adopt shapes that minimize repulsion between electron pairs. Therefore, they adjust to keep pairs of valence electrons as far apart as possible, which is crucial for determining molecular geometry.

What is the VSEPR theory used to predict?

• Bond Strength

• Polarity

• Molecular Shape

• Electronegativity

Answer explanation

VSEPR theory, or Valence Shell Electron Pair Repulsion theory, is used to predict the molecular shape of a molecule based on the repulsion between electron pairs around a central atom, making 'Molecular Shape' the correct choice.

Which of the following molecular shapes would have a bond angle of 180 Degrees?

• Bent

• Trigonal Planar

• Tetrahedral

• Linear

Answer explanation

The linear molecular shape has a bond angle of 180 degrees due to its two bonding pairs arranged opposite each other. In contrast, bent, trigonal planar, and tetrahedral shapes have smaller bond angles.

What is the bond angle in H₂S molecule?

• 107^◦

• 104.5^◦

• 180^◦

• 120^◦

Answer explanation

The bond angle in H2S is approximately 104.5°. This is due to the presence of two lone pairs on the sulfur atom, which repel the hydrogen atoms, resulting in a bent molecular shape.

The bond angle for a trigonal planar molecule is 

• 90 Degrees

• 109.5 Degrees

• 120 Degrees

• 180 Degrees

Answer explanation

In a trigonal planar molecule, the three bonding pairs of electrons are arranged around the central atom to minimize repulsion, resulting in a bond angle of 120 degrees.

What is the bond angle for this molecule?

• 109.5

• 120

• 107

• 90

Answer explanation

The bond angle of 109.5 degrees is characteristic of a tetrahedral molecular geometry, which occurs when a central atom is bonded to four other atoms with no lone pairs, leading to this specific angle.

How many lone pairs of electrons will a bent molecule have on the central atom?

• 0

• 2

• 3

• 4

Answer explanation

A bent molecule typically has two lone pairs of electrons on the central atom, which contributes to its angular shape. Therefore, the correct answer is 2.

Which molecule would have this shape?

• BF₃

• CH₄

• PCl₅

• CO₂

Answer explanation

CO₂ has a linear shape due to its two double bonds and no lone pairs on the central carbon atom. In contrast, BF₃ is trigonal planar, CH₄ is tetrahedral, and PCl₅ is trigonal bipyramidal.

What molecule could this be? 

• BF₃

• CH₄

• H₂O

• CO₂

Answer explanation

BF3 is a trigonal planar molecule with a central boron atom bonded to three fluorine atoms, making it a strong Lewis acid. The other options (CH4, H2O, CO2) have different geometries and bonding characteristics.

Tags

NGSS.HS-PS1-3