2.2B VSEPR Theory

What are covalent bonds characterized by?

Every covalent bond is characterized by two values:

Bond length: the distance between bonded nuclei

Bond strength: the amount of energy needed to break the bond. It is also called bond enthalpy.

In general...

Shorter bonds are stronger bonds

In general, shorter bonds are ________ bonds

stronger

Tell me about Multiple Bonds in molecules

Atoms can share more than one pair of electrons to form multiple bonds.

A double bond forms when two pairs of electrons (4e^- in total) are shared

A triple bond forms when three pairs of electrons (6e^- in total) are shared

Multiple bonds have a greater number of shared electrons and so have a greater force of electrostatic attraction between the bonded nuclei.

What is the relationship between Bond Length and each quantity of bond?

Shortest: Triple Bonds < Double Bonds < Single Bonds :Longest

What is the relationship between Bond Strength/Enthalpy and each quantity of bond?

Lowest: Single Bonds < Double Bonds < Triple Bond :Highest

What does VSEPR stand for? What does it state?

electrons in covalent bonds and in lone pairs repel one another

Molecules have 3D shapes that place electron pairs on the central atom as far apart as possible.

What are the shapes of molecules determined by?

1. The number of atoms bound to the central atom

2. The number of lone pairs of electrons on the central atom

Electron domains can be what types of bonds?

single, double, triple bonding electron pairs or non-bonding pairs of electrons

What determines the geometric arrangements of electron domains?

the total number of electron domains

Why do lone pairs of electrons cause slightly more repulsion than bonding pairs?

Lone pairs of electrons have a higher concentration of charge