Chemistry 1045 CH. 10 Flashcards

Questions and Answers

What does bonding theory predict?

The shapes of molecules

What do the properties of molecular substances depend on?

The structure of the molecule

What are molecules considered to be?

3 dimensional objects

What are the characteristic angles of geometric figures called?

Bond angles Signup and view all the answers

What does Lewis theory predict?

Electron groups Signup and view all the answers

What principle does VSEPR Theory explain?

Electron groups around the central atom will be most stable when they are as far apart as possible Signup and view all the answers

Why should electrons be separated as much as possible?

Because they are negatively charged Signup and view all the answers

What does a Lewis structure predict?

The number of valence electron pairs around the central atom(s) Signup and view all the answers

What does each lone pair of electrons constitute?

One electron group on a central atom Signup and view all the answers

What does each bond constitute?

One electron group on a central atom, regardless of whether it is single, double, or triple Signup and view all the answers

How many basic arrangements of electron groups are there around a central atom?

Five Signup and view all the answers

What is the bond angle for linear geometry?

180 Signup and view all the answers

What is the bond angle for trigonal planar electron geometry?

120 Signup and view all the answers

What is the bond angle for tetrahedral electron geometry?

109.5 Signup and view all the answers

What is the geometry for five electron groups?

Trigonal bipyramidal Signup and view all the answers

What are the positions above and below the central atom in a trigonal bipyramidal arrangement called?

Axial positions Signup and view all the answers

What are the positions in the same base plane as the central atom in a trigonal bipyramidal arrangement called?

Equatorial positions Signup and view all the answers

What is the bond angle between axial and equatorial positions?

90 Signup and view all the answers

What is the geometry associated with six electron groups?

Octahedral Signup and view all the answers

How does molecular geometry differ from electron geometry?

The actual geometry of the molecule may be different from the electron geometry Signup and view all the answers

What affects bond angles in a molecular structure?

Lone pairs and repulsions Signup and view all the answers

What do lone pair groups do to electron groups?

They occupy more space Signup and view all the answers

What is the resulting shape when four electron groups around the central atom have one lone pair?

Pyramidal shape Signup and view all the answers

How does the presence of two lone pairs affect four electron groups around the central atom?

Results in a tetrahedral bent shape Signup and view all the answers

What type of shape results when there are three electron groups and one lone pair?

Trigonal planar bent shape Signup and view all the answers

What is the outcome when there are five electron groups and one lone pair?

Seesaw shape Signup and view all the answers

What is a result of five electron groups with two lone pairs?

T shaped Signup and view all the answers

What is the result of five electron groups with three lone pairs?

Linear shape Signup and view all the answers

The bond angles between equatorial positions are less than what value?

120 Signup and view all the answers

What is the bond angle between axial and equatorial positions less than?

90 Signup and view all the answers

What shape results from six electron groups with one lone pair?

Square pyramidal shape Signup and view all the answers

What shape results from six electron groups with two lone pairs?

Square planar shape Signup and view all the answers

What is the first step in predicting the shapes around central atoms?

Draw the Lewis structure Signup and view all the answers

What affects polar molecules?

They must have polar bonds and an unsymmetrical shape Signup and view all the answers

How are polar molecules attracted?

To other polar molecules Signup and view all the answers

Who is associated with Valence Bond Theory?

Linus Pauling Signup and view all the answers

What do molecular orbitals represent?

Regions of high probability of finding shared electrons Signup and view all the answers

In terms of stability, how do molecular orbitals compare to atomic orbitals?

Molecular orbitals are more stable than separate atomic orbitals Signup and view all the answers

What does hybridization entail?

Mixing different types of orbitals in the valence shell Signup and view all the answers

What type of bond results when atomic orbitals point along the axis connecting two bonding nuclei?

Sigma (σ) bond Signup and view all the answers

What type of bond results when bonding atomic orbitals are parallel to each other?

Pi (π) bond Signup and view all the answers

What type of hybridization yields the lowest overall energy for a molecule?

Hybridization that maximizes bonding opportunities Signup and view all the answers

Study Notes

Bonding Theory and Molecular Shapes

Bonding theory predicts the shapes of molecules, influencing their properties.
Molecules exist as three-dimensional structures with specific bond angles.
Lewis theory helps in predicting molecular shapes based on electron groups around central atoms.

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory states that electron groups are most stable when maximally separated, minimizing repulsions.
Electrons repel each other due to negative charges; optimal separation results in predictable shapes and bond angles.

Electron Group Geometry

Five basic arrangements of electron groups yield distinct geometries: linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral.
Lone pairs occupy more space than bonding pairs, affecting molecular geometry and bond angles.

Molecular Geometry Types

Linear Geometry for two electron groups leads to a bond angle of 180°.
Trigonal Planar with three electron groups has a bond angle of 120°.
Tetrahedral Geometry with four electron groups has a bond angle of 109.5°.
Trigonal Bipyramidal with five groups includes axial (90°) and equatorial (120°) positions.
Octahedral Geometry for six groups results in bond angles of 90°.

Effects of Lone Pairs

Lone pairs influence molecular shape by occupying more space and affecting bond angles.
Molecular geometries can diverge from ideal shapes due to lone pairs, leading to shapes such as pyramidal, bent, or T-shaped.

Specific Geometric Shapes

Derivatives of trigonal bipyramidal geometry include seesaw (one lone pair), T-shaped (two lone pairs), and linear (three lone pairs).
Derivatives of octahedral geometry include square pyramidal (one lone pair) and square planar (two lone pairs).

Hybridization and Bonding

Hybridization involves combining orbitals to maximize bonding potential, producing hybrid orbitals.
Orbital interactions create molecular orbitals, with stability resulting from paired electrons.
Sigma (σ) bonds form through head-on overlap; pi (π) bonds form via parallel approach.

Bonding and Stability

σ bonds are stronger than π bonds, allowing for free rotation without breaking the bond.
Hybrid or nonhybrid hybrid orbitals interact to form σ bonds; π bonds require breaking orbital interactions for rotation.

Multiple Central Atoms

Complex molecules can have multiple central atoms, requiring sequential shape descriptions for each atom based on their electron group arrangements.

Polarity of Molecules

To be polar, a molecule must contain polar bonds, exhibit electronegativity differences, and have an asymmetrical shape.
Polar molecules attract other polar molecules, affecting solubility properties, such as in water.

Summary of Bonding Concepts

Valence Bond Theory blends quantum mechanics with chemistry, focusing on hybridization and molecular geometry.
sp, sp², and sp³ hybridizations define molecular shapes corresponding to different numbers of electron groups.
Use drawings reflecting three-dimensional shapes and bonds to convey molecular structures effectively.

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Description

This quiz focuses on Chapter 10 of Chemistry 1045, covering key concepts related to bonding theory and molecular geometry. Flashcards highlight fundamental definitions and properties of molecular substances, including shapes and bond angles. Perfect for students needing to review chapter material.