Copyright

London Dispersion Forces (Van Der Waal's Forces): Weak Intermolecular Forces

  • 0:05 London Dispersion Force
  • 1:16 Weakness of Force
  • 2:01 Effects on Properties
  • 3:53 Lesson Summary
Create An Account
To Start This Course Today
Used by over 10 million students worldwide
Create An Account
Try it free for 5 days
Lesson Transcript
Instructor: Amy Meyers

Amy holds a Master of Science. She has taught science at the high school and college levels.

Learn how London dispersion forces are created and what effect they have on properties such as boiling and melting points. Discover this weak intermolecular force and how it is one of the van der Waals forces.

London Dispersion Force

You know that every atom and molecule has electrons and that these electrons are in constant motion. At any one instant in time, these electrons can be more towards one side of a molecule than another. When the electrons are concentrated more at one end of a molecule, that end becomes slightly negative. The other end, where the electrons are not as concentrated, becomes slightly positive. At this instant, this molecule is a temporary dipole. This dipole can encourage a nearby molecule to also become dipole because the negative side of the first molecule will cause the electrons to run away on the other molecule (since negative (-) detests negative (-)).

Now these two adjacent dipoles created from the movement of electrons are attracted to each other. This very weak intermolecular force is called London dispersion force. London dispersion force is the weak intermolecular force that results from the motion of electrons that creates temporary dipoles in molecules. The London dispersion force is sometimes called a 'van der Waals force.' Van der Waals force is a general term that describes any attractive intermolecular force between molecules and includes both the London dispersion force and the dipole-dipole force discussed elsewhere.

The London dispersion force causes the attraction of adjacent dipoles.
Diploes Attracted to Each Other

Weakness of Force

As you can imagine, this is an extremely weak force - much weaker than hydrogen bonding or any other intramolecular force. As I mentioned, this force works between all atoms and molecules. This is the only intermolecular force that works on noble gases and nonpolar molecules.

A London dispersion force works because of the movement of electrons. As you can imagine, the more electrons in the atoms, the stronger the force. Also, in a larger atom, the electrons are going to be filling the higher energy shells, which means they will be farther away from the nucleus and thus be less tightly held by the nucleus' attraction. The electrons farthest away are able to move more freely, creating a dipole easier. This is why the London force increases with increasing atomic mass.

To unlock this lesson you must be a Study.com Member.
Create your account

Unlock Your Education

See for yourself why 10 million people use Study.com

Become a Study.com member and start learning now.
Become a Member

Already a member? Log In

Earning College Credit

Did you know… We have over 100 college courses that prepare you to earn credit by exam that is accepted by over 2,900 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Click "next lesson" whenever you finish a lesson and quiz. Got It
You now have full access to our lessons and courses. Watch the lesson now or keep exploring. Got It
You're 25% of the way through this course! Keep going at this rate,and you'll be done before you know it.
1
The first step is always the hardest! Congrats on finishing your first lesson.
5
Way to go! If you watch at least 30 minutes of lessons each day you'll master your goals before you know it.
10
Congratulations on earning a badge for watching 10 videos but you've only scratched the surface. Keep it up!
20
You've just watched 20 videos and earned a badge for your accomplishment!
50
You've just earned a badge for watching 50 different lessons. Keep it up, you're making great progress!
100
You just watched your 100th video lesson. You have earned a badge for this achievement!
200
Congratulations! You just finished watching your 200th lesson and earned a badge!
300
Congratulations! You just finished watching your 300th lesson and earned a badge!
500
You are a superstar! You have earned the prestigious 500 video lessons watched badge.
1K
Incredible. You have just entered the exclusive club and earned the 1000 videos watched badge.
20
You have earned a badge for watching 20 minutes of lessons.
50
You have earned a badge for watching 50 minutes of lessons.
100
You have earned a badge for watching 100 minutes of lessons.
250
You have earned a badge for watching 250 minutes of lessons.
500
You have earned a badge for watching 500 minutes of lessons.
1K
You have earned a badge for watching 1000 minutes of lessons.