Name That Element!

German chemist Martin Klaproth first identified the mystery element in 1789. It’s most commonly found combined with other elements in the form of a black mineral called pitchblende. But in its pure form, the mystery element is a silvery-white metal. It’s also the heaviest naturally occurring element on the periodic table. A 10 centimeter (4 inch) cube would weigh 20 kilograms (44 pounds)—about as much as the average kindergartner! Game over already? Score 100 points. If not, read clue 2.

German chemist Martin Klaproth first identified the mystery element in 1789. It’s most commonly found combined with other elements. This black mineral is called pitchblende. But in its pure form, the mystery element is a silvery-white metal. It’s also the heaviest naturally occurring element on the periodic table. A 10 centimeter (4 inch) cube would weigh 20 kilograms (44 pounds). That’s about as much as the average kindergartner! Game over already? Score 100 points. If not, read clue 2.

The mystery element led to the discovery of radioactivity—the emission of high-energy particles or rays as atoms with unstable nuclei break down over time. In 1897, French physicist Henri Becquerel left a crystal containing the mystery element on a photographic plate (a glass plate used to take pictures before the invention of film). A splotch shaped like the crystal appeared on the plate. Becquerel concluded that the crystal must be emitting its own energy. We now know that many inner transition metals, like the mystery element, are radioactive. Figured it out? Score 80 points. Still playing? Check out clue 3.

The mystery element led to the discovery of radioactivity. A radioactive element has atoms with unstable nuclei. They break down over time and release high-energy particles or rays. In 1897, French physicist Henri Becquerel left a crystal containing the mystery element on a photographic plate. (These glass plates were used to take pictures before the invention of film.) A spot appeared on the plate. It was shaped like the crystal. Becquerel concluded that the crystal was emitting its own energy. The mystery element isn’t the only radioactive element. We now know that many other inner transition metals are too. Figured it out? Score 80 points. Still playing? Check out clue 3.

People use the mystery element to produce about 10 percent of the world’s electricity. “A single pound [of this element] can generate as much energy as 1,500 tons of coal,” says Al Sattelberger, a chemist at Argonne National Laboratory in Illinois. The element is used in nuclear power plants to fuel nuclear fission. During this reaction, a neutron hits an atom of the mystery element, causing it to split. This releases energy and more neutrons, which split other atoms of the mystery element, causing a chain reaction that releases even more energy. Got it? Score 60 points. Not sure? Try the next clue.

About 10 percent of the world’s electricity comes from the mystery element. “A single pound [of this element] can generate as much energy as 1,500 tons of coal,” says Al Sattelberger. He’s a chemist at Argonne National Laboratory in Illinois. The element is used in nuclear power plants. It fuels nuclear fission. During this reaction, a neutron hits an atom of the mystery element. The atom splits. This releases energy and more neutrons. These neutrons split other atoms of the mystery element. The result is a chain reaction that releases even more energy. Got it? Score 60 points. Not sure? Try the next clue.

In about a decade, NASA plans to send the first astronauts to Mars. A spacecraft that relies on the mystery element could get them there. Many spacecraft built to explore our solar system use plutonium (Pu) as an energy source. It’s found in the same period, or row, on the periodic table as the mystery element. The mystery element, though, could supply much more power—enough to send astronauts and all their supplies on the 225 million kilometer (140 million mile) trip to Mars and back. All done? Score 40 points. Still need help? There’s one more clue.

NASA plans to send the first astronauts to Mars in about a decade. The mystery element could help a spacecraft get them there. Plutonium (Pu) is an energy source for many spacecraft that explore our solar system. Plutonium and the mystery element are found in the same period, or row, on the periodic table. But the mystery element could supply much more power. It could send astronauts and all their supplies on the 225 million kilometer (140 million mile) trip to Mars and back. All done? Score 40 points. Still need help? There’s one more clue.

About 200 years ago, people began adding the mystery element to glassware to give it a yellowgreen color. Glass made this way glows bright green under ultraviolet (UV) light. These invisible energy waves cause the mystery element in the glass to fluoresce, or absorb one color of light energy and reemit it as a different color. But the mystery element also makes the glass slightly radioactive, which can be dangerous. As a result, the element, which has 92 protons in its nucleus, was banned in the U.S. and Europe for use as a coloring agent in the 1940s. Write your answer and score 20 points. Then continue.

About 200 years ago, people began adding the mystery element to glassware. This element gave the glass a yellow-green color. Glass made this way glows bright green under ultraviolet (UV) light. These invisible energy waves cause the mystery element in the glass to fluoresce. It absorbs one color of light energy and releases it as a different color. But the mystery element, which has 92 protons in its nucleus, also makes the glass slightly radioactive. That can be dangerous. So the U.S. and Europe banned this element as a coloring agent in the 1940s. Write your answer and score 20 points. Then go on.