VSEPR Theory

Two Assumptions Of VSEPR

1) Because electron pairs (clouds) are negative and repel each other, they spread out into 3-D space to get as far away from each other as possible. This minimizes repulsion and maximizes stability. 2) Lone pairs (unshared pairs / nonbonding pairs) of electrons take up more space and repel more than shared pairs. These are what?

Molecular Polarity

1) Draw the Lewis dot structure. 2) Draw the VSEPR structure 3) Is there a lone pair of electrons on the central atom? - Yes: polar molecule - No: next question 4) Are any bonds or atoms different or are they all the same? - Yes: polar molecule - No: non-polar molecule This is how to find ________________________ ___________________.

How To Determine Molecular Geometry

1) We can use the two assumptions of VSPER and the Lewis structure to predict shapes. 2) Draw the Lewis dot structure. 3) Count the number of bonding sites around the central atom. 4) Count the number of unshared pairs. 5) Use the information from #3 and #4 to decide the appropriate molecular geometry. These are the steps for what?

Linear

2 Bonds, 0 Lone Pairs, 180 degree bond angle.

Bent

2 bonds, 1 lone pair.

Bent

2 bonds, 2 lone pairs.

Single Bond

2 electrons, 1 bonding site.

Trigonal Planar

3 bonds, 0 lone pairs.

Trigonal Pyramidal

3 bonds, 1 lone pair.

Tetrahedral

4 bonds, 0 lone pairs.

Double Bond

4 electrons, 1 bonding site.

Triple Bond

6 electrons, 1 bonding site.

Smallest

Bent has the __________________ bond angle.

Only

Electron domain geometry is ___________ different if there is a lone pair.

Polar

If there is a lone pair, the bond is ____________ or all of the outside atoms are not the same.

Octet Theory

Is an atom's preference to have a full valence shell of eight electrons. When atoms have fewer electrons in the shell, they tend to attract other atoms to create a stable compound.

Extra Electrons

Lone pairs are bonded to the central atom as ___________ _____________________.

Polarity

Means there is partial charge throughout the atom.

Shorter And Stronger

Multiple bonds are _____________ ________ ________________ than a single bond.

Closer

Nonbonding pairs of electrons are held _______________ to the central atom and force the bonds _______________ together.

Bond Length

Single > Double > Triple

Solid Triangle

The ____________ ________________ represents a bond coming out of the screen.

Dashed Triangle

The ______________ ________________ represents a bond going back into the board.

Domain

The electrons in bonds (bonding domains) differ from lone pairs because they are bonded to the central atom as a ________________.

Molecular Geometry

The molecular structure, is the three-dimensional structure or arrangement of atoms in a molecule. Understanding the molecular structure of a compound can help determine the polarity, reactivity, phase of matter, color, and magnetism.

Electron Domain Geometry

The three-dimensional arrangement of the electron domains around an atom according to the VSEPR model.

Domain

Think of lone pairs of electrons or a bond as a "___________" of electrons. Single bond, double bond, triple bonds each count as one ________________.

VSEPR Theory

This theory allows us to predict the shape of the molecule.

Bond Strength

Triple > Double > Single

Valence Shell Electron Pair Repulsion

What does VSEPR stand for?

Tetrahedral

When the atoms exist in 3-D and once you have 4e- clouds around the central atom the molecules are no longer flat (planar).

D. only one of the molecules is polar.

Which is the correct description of polarity in F2 and HF molecules? A. both molecules contain a polar bond. B. neither molecule contains a polar bond. C. both molecules are polar. D. only one of the molecules is polar.

A. repulsive forces between the outer levels of electron clouds.

Which of the following is the major factor in the determination of molecular shape? A. repulsive forces between the outer levels of electron clouds. B. attractive forces between the nucleus of one atom and the electrons of another. C. repulsive forces between the nuclei of the atoms. D. the relative amount of shielding effect within the atoms.

Lone Pairs

___________ ____________ have more repulsion and bonding energy than bonded pairs.

Nonbonding

___________________ pairs of electrons cause the expected bond angle to decrease by a small amount and cannot be seen.