Gen Chem Chapter 9-Theories of Bonding and Structure

These flashcards cover key concepts from the lecture on the theories of bonding and structure in chemistry.

What does VSEPR stand for?

Valence Shell Electron Pair Repulsion.

What are the five basic molecular geometries?

Linear, Trigonal Planar, Tetrahedral, Trigonal Bipyramidal, Octahedral.

What does the VSEPR model predict?

The shape of molecules and ions based on electron domain repulsions.

What is the influence of molecular shape on polarity?

It affects the dipole moment of molecules.

What is the role of hybridization in bonding?

It refines valence bond theory by combining atomic orbitals to form new orbitals.

How are shapes classified in VSEPR theory?

According to the number of electron domains around the central atom.

What are the two types of electron domains?

Bonding domains and nonbonding (lone pair) domains.

What does a linear molecular shape indicate?

There are 2 electron domains around the central atom.

What molecular geometry corresponds to 3 electron domains with 0 lone pairs?

Planar Triangular.

What molecular shape does 4 electron domains with 1 nonbonding domain take?

Trigonal Pyramid.

In VSEPR theory, how do lone pairs affect molecular geometry?

Lone pairs take up more space and can distort bond angles.

What are the bond angles in a tetrahedral molecular shape?

109.5 degrees.

What structure does 5 bonding domains lead to?

Trigonal bipyramidal.

How are multiple bonds treated in VSEPR theory?

As a single electron domain.

What shape corresponds to 3 bonding domains and 2 nonbonding domains?

T-shape.

What is the bond angle in an octahedral molecular shape?

90 degrees.

How do electronegativity values contribute to molecular polarity?

Higher electronegativity creates a negative dipole, while lower creates a positive dipole.

What signifies that a molecule is polar?

It has a net dipole moment, with an uneven distribution of charge.

What must happen for a molecule to be nonpolar?

The bond dipoles must cancel each other out.

What is the significance of resonance structures?

They represent different forms a molecule can take with the same connectivity.

What does molecular orbital theory explain?

The nature of bonding in diatomic molecules and properties like magnetism.

How do bonding molecular orbitals form?

From constructive interference of atomic orbital wave functions.

What is the difference between bonding and antibonding molecular orbitals?

Bonding orbitals stabilize a molecule, whereas antibonding orbitals destabilize it.

What happens to molecular stability as bond order increases?

Bond length decreases and bond energy increases.

What does a bond order of 1 indicate?

The presence of a single bond.

What do pi bonds result from?

Sideways overlap of unhybridized p orbitals.

What is a sigma bond?

A bond formed by the head-on overlap of orbitals.

What does molecular orbital energy diagrams illustrate?

Energy levels of molecular orbitals relative to atomic orbitals.

How do you determine the bond order from a molecular orbital diagram?

(Number of bonding electrons - Number of antibonding electrons)/2.

What diatomic molecule consists of sp hybridized carbons and has a triple bond?

Ethyne (C2H2).

In terms of hybridization, how do lone pairs affect the geometry?

Lone pairs must be counted when determining molecular geometry.

What does the term 'delocalized molecular orbitals' mean?

Bonding molecular orbitals that extend across multiple atoms.

How is benzene represented in molecular orbital terms?

As having delocalized pi electrons over six carbon atoms.

What do the terms 'paramagnetic' and 'diamagnetic' refer to in molecular orbital theory?

Paramagnetic means having unpaired electrons, while diamagnetic means all electrons are paired.

What does the Heisenberg Uncertainty Principle state regarding electrons?

It is impossible to simultaneously know the exact position and momentum of an electron.

What is the key feature of molecular orbitals compared to atomic orbitals?

Molecular orbitals are spread over an entire molecule rather than localized around individual atoms.

What must be considered in the molecular polarity of asymmetrical molecules?

The geometry and arrangement of bonds in determining net dipole moments.

When is a molecule asymmetrical and therefore likely polar?

When it has different terminal atoms or lone pairs.

What are the orbital shapes resulting from hybridization?

They have new shapes and directional properties compared to parent atomic orbitals.

What happens to bond angles when lone pairs are present?

The bond angles are typically distorted and reduced.

In a tetrahedral molecule with lone pairs, what bond angles would be expected?

Less than 109.5 degrees.

What defines the geometry of a trigonal planar molecule?

Three bonding pairs and no lone pairs, resulting in 120-degree angles.