AP Chem VSEPR and Molecular Geometry
36 flashcards covering AP Chem VSEPR and Molecular Geometry for the AP-CHEMISTRY Unit 2 section.
VSEPR (Valence Shell Electron Pair Repulsion) theory and molecular geometry are key concepts in AP Chemistry, specifically outlined in the College Board's AP Chemistry Curriculum Framework. This topic focuses on how the arrangement of electron pairs around a central atom influences the shape of molecules, which is crucial for predicting molecular behavior and reactivity.
In practice exams and competency assessments, questions on VSEPR and molecular geometry often require students to predict molecular shapes based on Lewis structures or to identify the geometry of given molecules. Common traps include misinterpreting lone pairs as bonding pairs or overlooking the impact of multiple bonds on molecular shape. Students might also confuse similar geometries, such as trigonal planar and tetrahedral, which can lead to incorrect answers.
One practical tip is to always visualize the three-dimensional structure of molecules, as this can clarify the spatial arrangement of atoms and help avoid common misconceptions.
Terms (36)
- 01
What is the VSEPR theory used for?
VSEPR theory is used to predict the three-dimensional shape of molecules based on the repulsion between electron pairs around a central atom, helping to determine molecular geometry (College Board AP CED).
- 02
How does lone pair presence affect molecular geometry?
Lone pairs of electrons occupy more space than bonding pairs, causing greater repulsion and altering the predicted bond angles and overall geometry of the molecule (College Board AP CED).
- 03
What molecular shape corresponds to a steric number of 4 with no lone pairs?
The molecular shape is tetrahedral when the steric number is 4 and there are no lone pairs on the central atom (College Board AP CED).
- 04
Which molecular geometry is associated with a steric number of 3 and one lone pair?
The molecular geometry is trigonal pyramidal when the steric number is 3 and one lone pair is present (College Board AP CED).
- 05
What is the bond angle in a trigonal planar molecule?
The bond angle in a trigonal planar molecule is approximately 120 degrees (College Board AP CED).
- 06
How is the molecular geometry of a molecule determined?
Molecular geometry is determined by the arrangement of electron pairs and atoms around a central atom, as predicted by VSEPR theory (College Board AP CED).
- 07
What is the shape of a molecule with a steric number of 2?
The shape of a molecule with a steric number of 2 is linear (College Board AP CED).
- 08
What is the bond angle in a tetrahedral molecular geometry?
The bond angle in a tetrahedral molecular geometry is approximately 109.5 degrees (College Board AP CED).
- 09
What molecular geometry results from a steric number of 5 with one lone pair?
The molecular geometry is seesaw when the steric number is 5 and there is one lone pair (College Board AP CED).
- 10
Which molecular geometry has a steric number of 6 and no lone pairs?
The molecular geometry is octahedral when the steric number is 6 and there are no lone pairs (College Board AP CED).
- 11
What is the effect of multiple bonds on molecular geometry?
Multiple bonds count as one region of electron density in VSEPR theory, affecting the molecular shape but not the steric number (College Board AP CED).
- 12
What is the geometry of a molecule with two bonding pairs and one lone pair?
The geometry is bent or angular when there are two bonding pairs and one lone pair around the central atom (College Board AP CED).
- 13
How does VSEPR theory explain the shape of water (H2O)?
VSEPR theory explains that water has a bent shape due to two bonding pairs and two lone pairs on the oxygen atom, leading to a bond angle of about 104.5 degrees (College Board AP CED).
- 14
What is the molecular geometry of carbon dioxide (CO2)?
The molecular geometry of carbon dioxide is linear due to the arrangement of two double bonds and no lone pairs on the central carbon atom (College Board AP CED).
- 15
What is the bond angle in a molecule with trigonal bipyramidal geometry?
In a trigonal bipyramidal geometry, the bond angles are 120 degrees in the equatorial plane and 90 degrees between the axial and equatorial positions (College Board AP CED).
- 16
What is the molecular shape of ammonia (NH3)?
The molecular shape of ammonia is trigonal pyramidal due to three bonding pairs and one lone pair on the nitrogen atom (College Board AP CED).
- 17
How does the presence of lone pairs influence bond angles?
Lone pairs can decrease bond angles between bonding pairs due to increased repulsion, altering the ideal angles predicted by VSEPR (College Board AP CED).
- 18
What is the geometry of a molecule with four bonding pairs and one lone pair?
The geometry is seesaw when there are four bonding pairs and one lone pair around the central atom (College Board AP CED).
- 19
What molecular shape is associated with a steric number of 3 and no lone pairs?
The molecular shape is trigonal planar when the steric number is 3 and there are no lone pairs (College Board AP CED).
- 20
Which molecular geometry corresponds to a steric number of 5 with two lone pairs?
The molecular geometry is T-shaped when the steric number is 5 and there are two lone pairs (College Board AP CED).
- 21
What is the bond angle in a T-shaped molecular geometry?
The bond angles in a T-shaped molecular geometry are approximately 90 degrees between the axial and equatorial positions (College Board AP CED).
- 22
How does VSEPR theory predict the shape of methane (CH4)?
VSEPR theory predicts that methane has a tetrahedral shape due to four bonding pairs and no lone pairs on the carbon atom (College Board AP CED).
- 23
What is the molecular geometry of sulfur tetrafluoride (SF4)?
The molecular geometry of sulfur tetrafluoride is seesaw due to four bonding pairs and one lone pair on the sulfur atom (College Board AP CED).
- 24
What is the bond angle in a bent molecular geometry?
The bond angle in a bent molecular geometry is typically less than 120 degrees, depending on the number of lone pairs (College Board AP CED).
- 25
What is the shape of a molecule with a steric number of 2 and one lone pair?
The shape is bent when there is a steric number of 2 and one lone pair on the central atom (College Board AP CED).
- 26
How does VSEPR theory apply to predicting molecular shapes?
VSEPR theory applies by considering the repulsion between electron pairs to predict the arrangement of atoms in three-dimensional space (College Board AP CED).
- 27
What is the molecular geometry of phosphorus pentachloride (PCl5)?
The molecular geometry of phosphorus pentachloride is trigonal bipyramidal due to five bonding pairs and no lone pairs (College Board AP CED).
- 28
What is the effect of hybridization on molecular geometry?
Hybridization affects molecular geometry by determining the geometry based on the types of orbitals mixed to form new hybrid orbitals (College Board AP CED).
- 29
What is the bond angle in an octahedral molecular geometry?
The bond angle in an octahedral molecular geometry is 90 degrees (College Board AP CED).
- 30
How does the presence of double bonds affect molecular shape?
Double bonds are treated as a single region of electron density in VSEPR theory, influencing the overall molecular shape but not the steric number (College Board AP CED).
- 31
What is the molecular shape of xenon tetrafluoride (XeF4)?
The molecular shape of xenon tetrafluoride is square planar due to four bonding pairs and two lone pairs on the xenon atom (College Board AP CED).
- 32
What is the bond angle in a square planar molecular geometry?
The bond angle in a square planar molecular geometry is 90 degrees (College Board AP CED).
- 33
What is the molecular geometry of a molecule with three bonding pairs and two lone pairs?
The molecular geometry is T-shaped when there are three bonding pairs and two lone pairs (College Board AP CED).
- 34
How does VSEPR theory address molecules with resonance?
VSEPR theory considers the average shape of resonance structures to predict the geometry of molecules with resonance (College Board AP CED).
- 35
What is the geometry of a molecule with five bonding pairs and no lone pairs?
The geometry is trigonal bipyramidal when there are five bonding pairs and no lone pairs around the central atom (College Board AP CED).
- 36
What is the molecular shape of a molecule with a steric number of 4 and two lone pairs?
The molecular shape is bent when the steric number is 4 and there are two lone pairs (College Board AP CED).