I Sense A Little Tension In The Room

Follow this link to a very interesting and entertaining video clip on water drops:
Why do water drops form into spheres? Why aren’t they flat instead? The short answer is “surface tension.” But what is it about water that causes this surface tension? For that, we have to take a brief trip into chemistry.
The water molecule is composed of one central oxygen atom flanked by two hydrogen atoms. The hydrogen atoms are each linked to the oxygen atom by what is called a covalent bond. This is a pair of electrons that, instead of “orbiting” around a single atom, “orbit” around both atoms in the bond. This draws the two atoms closer together and links them tightly.
However, this electron sharing is not equal. Oxygen is something of an electron hog, so the electrons spend more time around the oxygen than the hydrogen. Since the electrons have a negative charge, the oxygen atom is left with a partial negative charge. The electron-deficient hydrogen atoms develop a partial positive charge.
This makes each water molecule “polar” – with a positive pole and a negative pole. With this polarity, each water molecule behaves like a tiny little magnet. And we have all seen how magnets behave around one another. If they are oriented positive-to-negative, they will attract one another – a process known as “Hydrogen bonding.” (If they are oriented positive-to-positive or negative-to-negative, they will repel each other – and then bump into another water molecule until a positive-to-negative attraction occurs.)
This happens countless times within liquid water, thus forming several long “Conga lines” of water molecules hydrogen-bonded to one another. Because the water molecules are so strongly attracted to one another, they adhere to one another rather than breaking apart and going their separate ways. The spherical water drop is the final illustration of the great attraction that each water molecule has for others of its kind.
I’m afraid that my analogy of the Conga line will stick in your head. But it does help us to picture the intermolecular forces among water molecules that – through surface tension – make water drops into spheres.

One Response to I Sense A Little Tension In The Room

  1. avatar Steve McLean says:

    I forgot to say thanks to Tom Perkins for finding the video noted in today's blog. Thanks, Tom!

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