Happy Birthday, Periodic Table!

YouTube // Crash Course
YouTube // Crash Course

On March 6, 1869, Dmitri Mendeleev unveiled a remarkable discovery-slash-invention: the periodic table arranging the known elements. He showed it to the Russian Chemical Society, and chemistry was forever changed.

Mendeleev's discovery had profound implications. By arranging the elements mostly according to their atomic weight, noting that various periodic relationships occurred among elements, and grouping related elements together, Mendeleev's table predicted useful information about elements that had not yet been discovered. Although only 60 elements were on that original table, we can draw a straight line from Mendeleev's work to the periodic table we see everywhere today. (Note: Mendeleev's table was very text-heavy; the modern boxy design we know came about starting in the 1920s when Horace Deming drew it up.)

So how did Mendeleev come to create his periodic table, and how did it help chemists? Hank Green taught a great Crash Course Chemistry lesson about the whole thing, starting with Mendeleev's childhood. Settle back for 10 minutes, and learn a bit about something we often take for granted.

If you're looking for a shorter introduction, check out this TED-Ed lesson. You might also be interested to know that German chemist Julius Lothar Meyer independently discovered the same thing in 1870, after working on a similar idea for years. So it goes.

A Low-Carb Diet Could Shorten Your Lifespan

iStock
iStock

The Atkins, Paleo, and Keto diets may have different gimmicks, but they all share a common message: Carbs are bad and meat is good. Yet a new analysis reported by New Scientist suggests that anyone who buys into this belief may later come to regret it. According to the paper, published in The Lancet Public Health, people who eat a moderate amount of carbs actually live longer than those who avoid them.

For their study, researchers analyzed data previously collected from 15,400 participants in the U.S. They found that people who received about 50 to 55 percent of their calories from carbohydrates had the longest lifespans, roughly four years longer than those who got 30 percent or less of their energy from carbs.

This doesn't necessarily mean that the key to a healthy diet is to stock your pantry with pasta and croissants. The study also showed that people who got up to 70 percent or more of their energy from carbs died one year earlier on average than subjects in the 50 to 55 percent group. A closer examination at the eating of habits of people who ate fewer carbs revealed another layer to the phenomenon: When people avoided carbohydrates in favor of meat, their chances of early death rose, but the opposite was true for people who replaced carb-heavy foods with plant-based fats and proteins, such as nuts, beans, and vegetables.

These numbers point to something dietitians have long been aware of: Eating a diet that's based around animal products isn't ideal. Getting more of your protein from plant-based sources, on the other hand, can lower your blood pressure and reduce your risks of type 2 diabetes, heart disease, and certain cancers. Nonetheless, fad diets that forbid people from eating carbs while letting them eat as much steak as they want are still popular because they're an easy way to lose weight in a short amount of time. But as the research shows, the short-term results are rarely worth the long-term effects on your health.

[h/t New Scientist]

Why Is Pee Yellow?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your body is kind of like a house. You bring things into your body by eating, drinking, and breathing. But just like the things we bring home to real houses, we don’t need every part of what we take in. So there are leftovers, or garbage. And if you let garbage sit around in your house or your body for too long, it gets gross and can make you sick. Your body takes out the garbage by peeing and pooping. These two things are part of your body’s excretory system (ECKS-krih-tore-eee SISS-tem), which is just a fancy way of saying “trash removal.” If your body is healthy, when you look in the toilet you should see brown poop and yellow pee.

Clear, light yellow pee is a sign that your excretory system and the rest of your body are working right. If your pee, or urine (YER-inn), is not see-through, that might mean you are sick. Dark yellow urine usually means that you aren’t drinking enough water. On the other hand, really pale or colorless pee can mean you might be drinking too much water! 

Your blood is filtered through two small organs called kidneys (KID-knees). Remember the garbage we talked about earlier? The chemicals called toxins (TOCK-sins) are like garbage in your blood. Your kidneys act like a net, catching the toxins and other leftovers and turning them into pee.

One part of your blood is called hemoglobin (HEE-moh-gloh-bin). This is what makes your blood red. Hemoglobin goes through a lot of changes as it passes through your body. When it reaches your kidneys, it turns yellow thanks to a chemical called urobilin (yer-ah-BY-lin). Urobilin is kind of like food coloring. The more water you add, the lighter it will be. That's why, if you see dark yellow pee in the toilet, it's time to ask your mom or dad for a cup of water. 

To learn more about pee, check out this article from Kids Health. 

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