Intermolecular Forces

Intermolecular Forces

Intermlecular Forces Introduction

Origin of Inteolecular Forces:

• They are forces that chemically hold molecules together.
• They can be strong or weak.

How we classify Intermolecular Forces:

• We classify intermolecular forces by how they are formed and how they act. Some are stronger than others. 3 types: Dipole Dipole, London Dispersion Forces, and Hydrogen Bonding

Van Der Waal's Force:

• The attraction of between molecules. Two kinds: Dipole Dipole(stronger) and London Dispersion Forces(weaker).

Hydrogen Bonding:

• These are where hydrogen attracts to electronegative elements which is usually weaker than other intermolecular bonds.

Example: Phosphine(PH3) combines with hydroxide(OH) which has an H combine with the OH.

The Origin of Intermolecular Forces

• One reason they happen is when a polar molecule attracts to another polar molecule

• Another way these occur is when a very quick change in polarity in one element to attract to another element that is the opposite charge.

• The last way these can happen is when Hydrogen bonds with a highly electronegative element and it causes a great attraction.

Intermolcular vs Intramolecular

• Intermolecular Forces are the attraction between two molecules, while Intramolecular Forces are found within the element.
• Intermolecular Forces are tipically weaker than Intramolecular Forces due to the inside of the element needing to be held together very tightly.

Intramolecular Forces Are Strongest

Intermolecular Forces:

• (Strongest)Dipole-Dipole
• (Same Strength As Dipole-Dipole)Hydrogen Bond
• London Disersion Forces

DNA and Protiens are Intermolecular Forces we have in our bodies.

Intramolecular Forces show up in all of the Elements like Phosphorus and Oxygen.

Induced Dipole vs Permanent Dipole

Induced Dipoles are when an Ion comes along and induces a dipole in an atom or nonpolar molecule.

Permanent Dipoles are due to a difference in electronegativity between the atoms in a covalent bond.

Induced is caused by the movement of electrons in an atom or moleule, while Permanent is due to electronegativity between atoms and molecules.

The differences between permanent and induced dipoles are that permanent dipoles are made into the molecular structure, while induced dipoles happen on certain circumstances.

Intermolecular forces have permanent dipoles while intramolecular forces have induced and permanent dipoles.

Classification

• Intermolecular Forces Intro
• The Origin of Intermolecular Forces
• Intermolecular Force vs Intramolecular Force
• Induced vs Permanent Dipole
• Classification Diagram of IMFs
• Discuss the difference in density between ice and water
• Explore the Significance of exitance of intermolecular forces

Hydrogen Bonding

Dipole Dipole

London Dispersion

Density difference in ice and water

The density of water is 1.00 while the density of ice is 0.917

The positioning of the hydrogen bonds cause the ice to push other molecules away causing it to be less dense.

Water contains all of the Intermolecular Forces there are: Dipole-Dipole, Hydrogen Bonding, and London Dispersion Force.

Example: Anhydrous Calcium Sulfate

The structure of the Calcium Sulfate makes it be able to have a strong structure. It is used in building and a dentist can use t for molding, casting, and dying. It is important to keep its structure or it would not be helpful in the ways it is now.