Lewis Structures & Bonding
What is a limitation of Lewis structures?
They do not accurately represent three-dimensional molecular shapes.
In molecular orbital theory, what happens when electron waves constructively interfere?
Bonding orbitals form.
What is the key principle behind VSEPR theory?
Charge repulsion of valence shell electrons determines molecular arrangement.
What determines whether a molecule is polar?
The molecular geometric symmetry and electronegativity differences.
Sigma bonds are formed when orbitals overlap along the bond axis.
True.
In valence bond theory, how do covalent bonds form?
When partially filled orbitals of two atoms overlap.
What determines whether a bond will form in molecular orbital theory?
The arrangement of electrons in bonding and antibonding orbitals.
In a tetrahedral molecule, what are the approximate bond angles?
109.5°
What is the steric number, geometric shape, bond angle, and hybridization for ethene (C₂H₄)?
Steric Number: 3, Shape: Trigonal planar, Bond Angle: 120°, Hybridization: sp².
Pi bonds are stronger than sigma bonds.
False.
What characterizes a sigma (σ) bond?
End-to-end orbital overlap along the bond axis.
What is orbital hybridization?
Combining orbitals with different energies to form new orbitals.
Why do bent molecules like water have a bond angle less than 109.5°?
Unbonded electron pairs cause greater repulsion.
What happens to atomic orbitals when a molecule forms, according to molecular orbital theory?
Atomic orbitals are completely replaced.
Some molecules can exist with fewer than eight valence electrons in their outer shell.
True.
What makes pi (π) bonds weaker than sigma bonds?
Electrons are spread out over a greater volume of space.
In orbital hybridization, why do atoms form hybrid orbitals?
To form stronger bonds by creating larger orbital lobes.
What characterizes a trigonal planar molecule?
Three regions of electrons with 120° bond angles.
What is the molecular dipole moment measured in, and what does it represent?
Measured in debyes, represents the vector sum of bond polarities.
Molecular orbital theory suggests that atomic orbitals remain unchanged when a molecule forms.
False.
What is a characteristic of hypervalent molecules?
The central atom has more than 8 valence electrons.
What does VSEPR stand for?
Valence Shell Electron Pair Repulsion Theory.
Name the steric number, geometric shape, bond angle, and hybridization for ammonia (NH₃).
Steric Number: 4, Shape: Trigonal pyramidal, Bond Angle: ~107°, Hybridization: sp³.
What happens to molecular shape due to lone pairs in a VSEPR structure?
Lone pairs repel bonded pairs, altering the molecular shape.
The molecular dipole moment represents the vector sum of bond polarities.
True