One of the great innovations of the twentieth century is likely not well-known, but this video from the Ri Channel is looking to change that:
This is X-ray crystallography.
Discovered in 1913 by William and Lawrence Bragg, x-ray crystallography is a technique that reveals the atomic and molecular structure of a crystal. When a narrow beam of x-rays is shown through the crystal, it diffracts into a pattern of rays through the other side.
"To date 28 Nobel Prizes have been awarded to projects related to the field" and 100 years after its discovery, the Curiosity Rover is using x-ray crystallography to analyze soil on Mars.
Science! And if you haven’t seen these yet, we’ve shared some of our favorite science videos for kids over at RiChannel.org, where they know great science videos.
How do you make a cloud? On her show, Head Rush, Mythbuster’s Kari Byron demonstrates how clouds are formed by making one in a bottle.
For this experiment, you can use a bicycle pump with a rubber stopper attachment, rubbing alcohol and a clear 1 liter bottle. Don’t forget goggles and some adult supervision! Steve Spangler’s Science has more:
The reason the rubbing alcohol forms a more visible cloud is because alcohol evaporates more quickly than water. Alcohol molecules have weaker bonds than water molecules, so they let go of each other more easily. Since there are more evaporated alcohol molecules in the bottle, there are also more molecules able to condense. This is why you can see the alcohol cloud more clearly than the water cloud.
Clouds on Earth form when warm air rises and its pressure is reduced. The air expands and cools, and clouds form as the temperature drops below the dew point. Invisible particles in the air in the form of pollution, smoke, dust or even tiny particles of dirt help form a nucleus on which the water molecules can attach.
From the archives: clouds and experiments.
Update: Here’s an even more simple version of the experiment! Thanks, @nicolasdickner.