Molecular Geometry and Polarity

Predicting the Shape

VSEPR stands for ______.

 It is the theory used to predict the three dimensional shape of a molecule.

 The most important factor in determining the geometry is the ______between electron pairs.

Molecules adopt the shape that ______the electron pair repulsions.

When looking at the charts………

Always use the ______atom.

A code can help you connect the molecule to its shape. An “A” stands for the ______atom and a “B” stands for the number of bonding atoms off the central atom. An “E” stands for the number of ______coming off the central atom.

Think ______of Electron density rather than bonds.

For example, a ______bond would only constitute ______region.

The 5 basic shapes are

Shape CodeMolecular Structure Example

LINEAR AB or AB2 HCl or

BeCl2

TRIGONAL PLANAR AB3BF3

TETRAHEDRAL AB4CH4

BENT or V-SHAPEDAB2E or AB2E2 H2O

TRIGONAL PYRAMIDAL AB3E NH3

Predicting the Polarity

Covalent Bonds can be classified as polar or nonpolar. A polar bond is between two nonmetals with different ______. A nonpolar bond is between 2 nonmetals with the ______electronegativity.

The entire molecule can also be classified as polar of nonpolar. When molecules have 2 distinct ends of charge, they are considered ______.

HCl is POLAR because it has a distinct______end and negative end.

We draw an arrow to represent the distance between the two charges ends. This is called a ______. Dipole arrows run from the least to the most ______.

H :Cl

The shape controls whether the dipoles cancel out or remain present. If they remain present, the molecule is ______. If they cancel out or were never present, the molecule is ______.

Examples

The polarity of a molecule can help predict the solubility of a substance.

Solubility is defined as the ability of a substance to ______into another.

Like Dissolves Like is a rule of thumb that helps us predict ______.

Polar substances dissolve polar substances.

Nonpolar substances dissolve nonpolar substances.

This is why ______and water do not mix.

Intermolecular Attractions

The weak attractions between 2 molecules are called ______.

They cause gas particles to stick together and ______at low temperature.

There are 2 types of intermolecular forces.

  1. ______forces are caused by random motion of the electrons. They are the ______of the two. They generally get stronger with more ______in the molecule.
  • Occur in all types of molecules
  • This force is the reason why bromine is a liquid and ______is a solid at room temperature.
  1. ______forces are caused by the positive side of one molecule

attracting the negative side of a different polar molecule. These are the ______of the two.

******A special type of dipole force is called ______bonding. It occurs only between the hydrogen of one polar molecule and the ______, ______, or ______of another polar molecule. It is the strongest intermolecular force that exists.