## Van der Waals

Posted in: Bond Breaker, Lesson Time! | September 10, 2014 | 2 Comments

One of the best parts of making a game based on science is that while playing the game… you learn science.  Even if you don’t mean to!  Take, for instance, the Van der Waals force.

(If you haven’t played Bond Breaker yet, give it a go.  It’ll make this all go down a little easier)

Van der Waals

The Electric Force, at its core, is pretty basic.  You can sum it up with: “opposites attract, likes repel.”  If you put two positive charges together, they’ll push away from each other.  And if you put a positive near a negative, they’ll attract together.  A neutral object, with no positive or negative charges, will be unaffected by the Electric Force.

In Bond Breaker, you can make a lot of ‘neutral’ object.  A Hydrogen molecule, for instance, consists of two protons and two electrons.  (+2) + (-2) = 0.  Put two of them near each other, and the Electric Force shouldn’t do anything, right?  Well, in Bond Breaker you can try that out!  Below is a little level I made (just for you, blog-post-reader), to test out what happens when neutral molecules are near one another.  Click it in your browser, and go play with the level (it’ll be called the ‘Bonus Level’).

Click the image to go play this BONUS Bond Breaker level!

Okay, so the molecules attract.  But if they’re all neutral, why?

Van der Waals forces.

These forces are what make molecules attract to one another (and form into liquids, say).  The weakest form of VdW force is called the “London Dispersion Force,” and it’s what you encounter in the game.

London Dispersion Forces

‘Neutral’ molecules are not simply neutral.  The positive and negative charges aren’t sitting right on top of one another.  At any given moment, the molecule will have a dipole moment — meaning one side will be more positive, and one side will be more negative.  Kind of like a bar magnet with a North pole and South pole.  Imagine putting a bunch of magnets into a bag and shaking them.  It won’t take long until they’re all stuck together.

With a molecules like Hydrogen that are very symmetrical, the dipole is completely random.  Sometimes you’ll find the electrons more on the north side of the molecule, sometimes you’ll find them on the south side.  And this makes the force pulling the molecules together very weak.  But it’s still there.

Van der Waals forces, though weak, end up being important in everything from forming liquids to helping geckos stick to walls.  So the next time you’re sitting in the pool, watching your pet gecko play Bond Breaker, you know what force to thank.

-Andy

1. #### By Dr_Loo

Posted September 10, 2014 at 2:42 pm | Permalink
• #### By TestTubeGames

Posted September 11, 2014 at 5:16 pm | Permalink

Cool, Dr. Loo — Thanks for sharing that!

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