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Quizzes > High School Quizzes > Science

Ace the VSEPR Quiz Practice Test

Boost your VSEPR theory skills for success

Difficulty: Moderate
Grade: Grade 10
Study OutcomesCheat Sheet
Paper art depicting a trivia quiz on molecular geometry for high school chemistry students.

What does VSEPR stand for?
Valence Shell Electron Pair Repulsion
Valence Shell Energy Particle Repulsion
Variable Shell Electron Pair Repulsion
Valence State Electron Pair Repulsion
VSEPR stands for Valence Shell Electron Pair Repulsion, which describes the repulsion between electron pairs in the valence shell of an atom. This repulsion forces the electron pairs to arrange themselves as far apart as possible, determining the molecular shape.
What basic principle does VSEPR theory rely on?
Electrons within a molecule attract each other.
Electron pairs repel each other due to their negative charge.
Electron pairs attract bonding electrons.
Atomic nuclei repel electron pairs.
VSEPR theory is based on the idea that electron pairs around a central atom repel each other because of their like negative charges. This repulsion forces them into an arrangement that minimizes energy and defines the molecule's geometry.
In VSEPR theory, how many electron groups around a central atom are needed to form a tetrahedral electron geometry?
3
4
5
6
A tetrahedral electron geometry occurs when there are four regions of electron density around a central atom. This arrangement allows the electron groups to be as far apart as possible, minimizing repulsion.
Which molecular geometry is associated with two electron groups around a central atom?
Bent
Trigonal Planar
Linear
Tetrahedral
When a central atom is surrounded by two electron groups, they position themselves on opposite ends of the atom, resulting in a linear geometry with a 180° bond angle. This is the simplest configuration in VSEPR theory.
Which molecule typically exhibits a bent molecular shape due to lone pairs on the central atom?
CO2
CH4
H2O
BF3
Water (H2O) has two bonding pairs and two lone pairs on the oxygen atom, forcing the molecule into a bent shape rather than a linear one. The lone pairs take up more space, compressing the bond angle.
What is the ideal bond angle in a molecule with tetrahedral geometry?
90°
109.5°
120°
180°
The ideal bond angle for a tetrahedral geometry is approximately 109.5°. This angle minimizes repulsion among the four electron groups surrounding the central atom.
How does the presence of lone pairs affect the bond angles in a molecule?
They increase the bond angles.
They have no effect on bond angles.
They reduce bond angles due to greater repulsion.
They always result in a linear geometry.
Lone pairs are more repulsive than bonding pairs because they are localized closer to the central atom. This enhanced repulsion compresses the bond angles between the bonding pairs.
Which molecular shape is observed in ammonia (NH3) according to VSEPR theory?
Tetrahedral
Trigonal Pyramidal
Linear
Trigonal Planar
Ammonia (NH3) has three bonding pairs and one lone pair around the nitrogen atom, leading to a trigonal pyramidal molecular shape. The lone pair distorts the ideal tetrahedral arrangement slightly.
A molecule with five regions of electron density and one lone pair adopts which molecular geometry?
Trigonal Bipyramidal
Seesaw
Pentagonal Bipyramidal
Square Pyramidal
When there are five electron groups with one lone pair, the molecule adopts a seesaw shape. The lone pair occupies an equatorial position, causing an asymmetrical distribution of the bonding pairs.
A molecule with a bent shape and four electron groups (two bonding pairs, two lone pairs) has what electron-pair geometry?
Tetrahedral
Trigonal Bipyramidal
Octahedral
Linear
Even though the observed molecular shape is bent, the total count of four electron groups gives a tetrahedral electron-pair geometry. The lone pairs alter the visible shape without changing the overall electron arrangement.
In VSEPR theory, how are double and triple bonds treated when counting electron groups?
They count as multiple electron groups.
They count as one electron group.
They are not counted at all.
They are counted as half an electron group.
In VSEPR theory, double and triple bonds are treated as a single electron group because the theory focuses on regions of electron density rather than the number of bonds. This simplification helps in predicting the overall molecular shape.
Which molecular geometry corresponds to a central atom with six regions of electron density?
Octahedral
Tetrahedral
Trigonal Bipyramidal
Square Planar
A central atom with six regions of electron density will adopt an octahedral geometry, which optimizes the separation between all electron groups. This arrangement minimizes repulsions effectively.
Which of the following molecules exhibits octahedral geometry as predicted by VSEPR theory?
PCl5
SF6
XeF2
NH3
SF6 has six bonding pairs around the central sulfur atom, which leads to an octahedral arrangement. This geometry is a classic example of the octahedral shape predicted by VSEPR for six electron groups.
A molecule with four electron groups around the central atom and one lone pair will have which molecular shape?
Seesaw
Trigonal Bipyramidal
Trigonal Pyramidal
Linear
With four electron groups the electron geometry is tetrahedral. The presence of one lone pair results in a trigonal pyramidal molecular shape as the lone pair occupies one of the tetrahedral positions.
For a molecule with five electron groups and two lone pairs, what is the molecular geometry?
Square Pyramidal
T-shaped
Seesaw
Trigonal Bipyramidal
When a molecule has five regions of electron density and two of them are lone pairs, the resulting molecular geometry is T-shaped. The lone pairs prefer equatorial positions, forcing the bonding pairs into a T-shaped structure.
Determine the molecular geometry of XeF2 using VSEPR theory.
Bent
Linear
Trigonal Planar
T-shaped
XeF2 has five regions of electron density around the xenon atom, including three lone pairs and two bonding pairs. The lone pairs are arranged equatorially, forcing the two fluorine atoms to adopt a linear arrangement.
Between CH4, NH3, and H2O, which molecule exhibits the greatest deviation from ideal bond angles due to lone pair repulsion?
CH4
NH3
H2O
All have the same bond angles
H2O exhibits the greatest deviation from ideal bond angles because it has two lone pairs, which exert stronger repulsive forces on the bonding pairs. This compression reduces the H - O - H bond angle to approximately 104.5°.
Which factor most significantly contributes to the distortion of ideal bond angles in molecules according to VSEPR theory?
The size of the central atom
The repulsion between lone pairs being greater than bonding pairs
The electronegativity differences between atoms
Hybridization of orbitals
The distortion of ideal bond angles is mainly due to the increased repulsion from lone pairs compared to bonding pairs. Lone pairs occupy more space and push the bonding pairs closer together, resulting in smaller bond angles.
Determine the molecular geometry of ClF3 using VSEPR theory.
T-shaped
Linear
Seesaw
Trigonal Bipyramidal
ClF3 has five regions of electron density with two lone pairs occupying equatorial positions, which results in a T-shaped molecular geometry. This arrangement minimizes repulsion between the electron groups in the molecule.
How do resonance structures affect molecular geometry predictions in VSEPR theory?
They significantly alter the predicted geometry.
They change the electron group count.
They do not affect the geometry as the electron pair distribution remains constant.
They only affect bond lengths but not bond angles.
Resonance structures represent different ways to distribute electrons, but they do not change the total electron pair distribution around the central atom. Therefore, the VSEPR predicted molecular geometry remains unchanged across resonance forms.
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Study Outcomes

  1. Understand the principles of VSEPR theory to explain molecular shape formation.
  2. Identify molecular structures based on bonding and lone pair arrangements.
  3. Apply VSEPR concepts to predict three-dimensional molecular geometries.
  4. Analyze the impact of electron pair repulsion on bond angles and molecule stability.
  5. Evaluate and compare molecular configurations to determine their geometrical outcomes.

VSEPR Quiz: Theory Review for Exams Cheat Sheet

  1. VSEPR theory fundamentals - VSEPR theory is like a molecular strategy game: it predicts shapes by arranging electron pairs to minimize repulsion around a central atom. Once you master it, you'll understand why water is bent and carbon dioxide is linear in no time. Purdue ChemEd: VSEPR Theory
  2. Identifying electron groups - Electron groups include single, double, triple bonds and lone pairs, and each plays a role in shaping molecules. Spotting them correctly ensures accurate geometry predictions. LibreTexts: Molecular Shapes
  3. Common molecular geometries - From linear and trigonal planar to tetrahedral, trigonal bipyramidal, and octahedral, these basic shapes are your building blocks in chemistry. Memorize them, and you'll decode countless molecular puzzles. Purdue ChemEd: Geometry Table
  4. Using AXE notation - AXE notation breaks down molecules into A (central atom), X (bonded atoms), and E (lone pairs), making shape determination a breeze. It's your shorthand for predicting angles and arrangements in seconds. Chemistry Talk: AXE Notation
  5. Lone pair crowding - Lone pairs hog more space than bonding pairs, often squeezing bond angles tighter than you'd expect. Remember this "bully effect" when you see deviations from ideal geometry. Purdue ChemEd: VSEPR Theory
  6. Practice with electron counts - The secret to mastering VSEPR is practice: count electron groups, apply the rules, and predict the shape. The more you drill, the more intuitive molecular geometry becomes. LibreTexts: VSEPR Applications
  7. Treating multiple bonds - In VSEPR, double and triple bonds count as one electron group, just like single bonds. This simplification keeps your predictions consistent. LibreTexts: Molecular Shapes
  8. Geometry and polarity link - Molecular shape directly affects polarity, which in turn influences boiling, melting points, and solubility. Visualize the 3D arrangement to predict physical properties. LibreTexts: Shape & Polarity
  9. Assessing molecular polarity - Check symmetry and bond dipoles: if they cancel, you've got a nonpolar molecule; if not, polarity is on the menu. This skill is key for predicting interactions in solutions. LibreTexts: Shape & Polarity
  10. Real-world applications - Apply VSEPR theory to molecules like ammonia, sulfur hexafluoride, and more to see their true shapes. Connecting theory to real examples cements your understanding and keeps study sessions interesting. Chemistry Talk: VSEPR Overview
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