Astatine : Unstable and Dangerous.

At last count, there are 118 confirmed elements in the periodic table – yet, out of that huge number, you’re more than nine times more likely to come into contact with just five than the other 113.

That’s because, out of all of the dozens of elements found in the Earth’s crust, it’s those five – oxygen, silicon, aluminum, iron, and calcium – which make up a total of more than 92 percent. In fact, almost half of the atoms we encounter every day are oxygen, making it by far the most abundant element on the planet.