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About "Ask A Scientist!"

On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 10 July, 2003 Next Week's Question
The cause of element 43's disappearing act
Question
Why is element 43 made by man and none of the elements around it are?

Question
Element 43, named technetium (Tc), isn't found naturally, but scientists can create it a nuclear reaction. In fact, technetium comes from the Greek word technetos, meaning artificial.

To answer your question, let's look at the structure of an atom. Atoms are made of particles called protons, neutrons, and electrons. Positively charged protons team up with neutrons, which have no charge, to form the core of an atom, the nucleus. Electrons create a negatively charged cloud around the nucleus. It's the number of protons that determines the name of each element. Finally, elements with different numbers of neutrons are called isotopes.

Protons have the same charge, so they repel each other. However, the dense nucleus is held together by what is called the strong force, which is very powerful. The nucleus likes to organize itself according to certain rules. If it's unhappy with its combination of protons and neutrons, it will eject particles, usually changing into a different element. In other words, it's radioactive! A similar situation occurs when you try to carry as many marbles in your hands as possible. You might start out with a bunch, but sooner or later you'll drop a few until you have a good grasp on the rest.

Technetium is unique because it has 43 protons and isn't stable with any number of neutrons. However, the elements next to Tc on the periodic table have a nice, stable combination of protons and neutrons. Tc would rather be like its neighbors. The 'half-life' is a measure of how long a radioactive element will last. After one half-life has passed, only half of the element is left. The longest-lived isotope of Tc has a half-life of 4,200,000 years, but the earth is over 1000 times older than that! That's why it's all gone today.

Where does it all go? It converts one neutron into a proton by ejecting an electron from the nucleus, becoming element 44, ruthenium.

A special manmade isotope of Tc is extremely useful in science and medicine today. The nucleus gives off extra energy by releasing high-energy light, called a gamma ray. The diagnosis of many illnesses is made possible by this isotope. Doctors inject Tc and use the gamma rays as tracers inside the body to image bones and several organs, including the brain and heart. It's like getting an X-ray from the inside out!

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