Chemistry

Chemistry is the science of matter and the changes it undergoes during chemical reactions. In this section, learn about everyday chemistry, from chlorine beach to helium, and even why chocolate turns gray.

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Biting on aluminum foil can be painful -- basically, when you bite on foil, you build a battery in your mouth. Ouch!

Smoking or chewing tobacco makes many people feel good, even mildly euphoric. It's the nicotine that produces the buzz. Find out how nicotine affects the human body and what makes it so addictive.

By Maria Trimarchi & Ann Meeker-O'Connell

More than 2.3 billion people across the globe drink alcohol, but most don't consider it a drug. But if you've ever seen someone who's had too much, you know alcohol has profound effects on the mind and body.

By Craig Freudenrich, Ph.D. & Michelle Konstantinovsky

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The air we breathe contains 21 percent oxygen. Would we be better off breathing 100 percent oxygen?

By Marshall Brain

Why do newspapers turn yellow over time?

Rust is the common name for iron oxide, which is created when iron bonds with oxygen. In fact, pure iron is only rarely found in nature because it interacts with oxygen so easily.

Here's something to consider: The place you call home likely has walls and glass windows. Both are adept at keeping rain, snow and wind from bothering you in your abode. Only one, though, allows light to enter. Why is that?

By William Harris

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Dynamite is simply some sort of absorbent material (like sawdust) soaked in nitroglycerin. But what makes this chemical so explosive?

Ever wondered exactly what they "artificial flavors" in your candy are, and why no specific ingredients are listed? Find out in this article.

By HowStuffWorks.com Contributors

If water is made up of hydrogen and oxygen, why can't we breathe underwater? It has to do with how molecules combine and how the human lung functions.

Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.

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Scenario: A helium balloon is up against the ceiling one day, and the next day it's on the floor. Does the balloon fall because the helium leaks out, or because the helium molecules slow down due to decreased pressure?

Helium is the second lightest element on the Periodic Table. How is helium created?

By Patrick J. Kiger

I recently used chlorine bleach to clean the siding on my house, and I was amazed at how well it worked! What is bleach? How does it remove stains? Is the chlorine in bleach the same as the chlorine in drinking water or in swimming pools? Is chlorine safe to use?

I have heard that carbon monoxide is extremely poisonous. Can you explain why?

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What is dioxin? There's a lot of discussion going on in my town about dioxin and its dangers.

If the idea of being completely knocked out by a cocktail of drugs while doctors operate on you freaks you out, you're not the only one. But that's not what anesthesia is all about it -- and it might scare you less if you understand how it works.

By Shanna Freeman

About 90 percent of Americans consume some form of caffeine every day: It's our most popular drug by far. What's so special about this stimulant?

By Marshall Brain, Charles W. Bryant & Matt Cunningham

Helium balloons tend to fascinate adults and children alike (and it's not just the Donald Duck voice thing, though that is a big draw). Learn all about helium and why it floats!

By Marshall Brain