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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We love it. We wear it glittering around our necks and sparkling at our ears, wrists and feet. We pass it down to our children and hoard it in secret stashes. Why is this precious metal so prized?

By William Harris

It begins with an unassuming "H" and ends in crazy elements that you've likely never heard of. But the periodic table, encapsulated on a mere sheet of paper, can be a scientist's best friend and a testament to our human drive to organize the world.

By Craig Freudenrich, Ph.D.

When it comes to stimulating the human central nervous system, meth can hold its shaky, toothless head high. Why is this drug so additive?

By Tom Scheve & Nathan Chandler

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Can you pass the acid test? That electric Kool-Aid changed the fabric of 1960's American counterculture. So, what's it's like to trip on LSD?

By Shanna Freeman & Nathan Chandler

Lead is one of the most maligned metals on the periodic table and for good reason. Lead poisoning is serious. But the beleaguered element isn't all bad, especially when it's protecting you from radiation.

By Craig Freudenrich, Ph.D.

Once considered a semiprecious metal alongside gold and silver, aluminum pretty much languished in obscurity until the 19th century. How did the metal become so ubiquitous?

By William Harris

Imagine spending your days racked with pain or losing pound upon pound because nausea leaves you unable to eat. Now imagine that someone offers you a wonder drug to cure all your ills. The problem? It's illegal.

By Jacob Silverman

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When you speak, a stream of air flows up your trachea from your lungs. And when you add helium, your voice rises several octaves. So if you filled the air with helium, just how high would your voice get?

By Marshall Brain

If you were to touch dry ice, it wouldn't be anything like touching water ice. So what's it like? Is it hot or cold? And would it leave a mark?

By Marshall Brain

We've all been told not to put aluminum foil in the microwave. Stories of incredible explosions and fires are usually at the center of these ominous warnings. Why is that?

By Marshall Brain

Most of us have heard the talk about oysters and chocolate, and maybe you've read an article about the stimulating effects of ginseng. But garlic, licorice and cucumber? Learn about the history of aphrodisiacs and whether they've been proven to be effective.

By Lee Ann Obringer

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Crack cocaine, like many other illegal drugs, leads to addiction, death, increased crime rates and imprisonment. But this drug targets the inner city almost exclusively and possession or distribution of crack carries extremely harsh prison sentences.

By Stephanie Watson & Nathan Chandler

Viagra is one of the best-known drugs of all time. Nearly every adult in America has heard of the drug and can tell you what it does. Find out how this high-profile medication works its magic.

By Marshall Brain & Katie Lambert

One person lay in critical condition on Feb. 29, 2008, after the deadly biotoxin ricin was found in his Las Vegas hotel room. What is ricin, and why is it so dangerous?

By Julia Layton

Have you seen investigators on crime shows who spray some stuff on a "clean" carpet and suddenly -- blood stains! Well, of all the fictional technology on TV, it turns out this stuff is real! Find out how luminol reveals the blood.

By Tom Harris

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You know how chocolate sometimes turns gray? Why does that happen and is it still OK to eat?

By HowStuffWorks.com Contributors

Marijuana isn't just a recreational drug for hippies and philosophy majors -- its psychoactive history ranges from Egyptian mummies to modern U.S. politics. What's the big deal about this leafy, green plant?

By Kevin Bonsor & Nicholas Gerbis

I recently bought a pair of mirrored sunglasses and they are already scratched. Isn't there a way to make them scratch-resistant?

What is dye-sublimation printing? Why is it better for printing digital images than traditional ink-jet printing?

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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

We need oxygen to live, so it seems to me that if we got more oxygen, we would be better off. Is it harmful to breathe 100-percent oxygen? What will happen?

By Marshall Brain

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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.