November 6, 2010

Discovery of two new elements announced--

on a kids' quiz show??? – 1945

The normal sober, serious announcement of scientific discoveries was delayed in the case of the heavy elements americium and curium. Why? Because of a little thing called World War II.

Scientists working at University of California, Berkeley, produced these radioactive metals while working with the Manhattan Project. This top-secret project was an attempt to understand and control the process of nuclear fission—that is, an attempt to split atoms and to create a horrible new weapon, the atomic bomb.

(By the way, the main site of the Manhattan Project was Los Alamos, New Mexico—an entire town that was kept secret during the war. I just went there and visited historical and scientific museums. Very interesting!)

Because of the secrecy of the Manhattan Project, the two new elements could not be revealed until after the war. It was planned that they would be officially unveiled at a meeting of the American Chemical Society, but five days before that (November 6, 1945), head scientist Glenn Seaborg chose to make the announcement on a radio show for kids, the Quiz Kids.

What do you think curium and americium are named for?

ANSWERS: Curium is named for the scientists Marie and Pierre Curie, who discovered radium and worked on radioactivity. It is the first element to be named for a historical person. Americium is named for America, the continent on which the element was first created. This name is an analogy to europium (named for Europe in the early 1900s). Later elements made by U.C. Berkeley scientists include californium and berkelium.

Atomic Numbers

The higher an element's atomic number, the larger and heavier that element's atoms are.

The lightest element is hydrogen. Most hydrogen atoms have only one proton and one electron. The atomic number of an element is the number of protons it has, so hydrogen's atomic number is 1.

Americium is atomic number 95. It has 95 times more protons than hydrogen does! Plus, each atom is a LOT heavier, because it has around 148 neutrons, too!

Curium is atomic number 96. The average curium atoms has 151 neutrons.

Both of these elements are considered unstable. Without any outside help, they break down into smaller elements, releasing radiation. This is what we mean when we say that these elements are radioactive.

  • Here is an interactive Periodic Table of the Elements.
  • Play a very element-ary game
  • Watch videos about the elements (including today's stars, Am and Cm). 

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