Login Become a Member Contact Us. March 1, Henri Becquerel Discovers Radioactivity In one of the most well-known accidental discoveries in the history of physics, on an overcast day in March , French physicist Henri Becquerel opened a drawer and discovered spontaneous radioactivity.
Henri Becquerel was well positioned to make the exciting discovery, which came just a few months after the discovery of x-rays. Becquerel was born in Paris in into a line of distinguished physicists.
In Becquerel began studying fluorescence and phosphorescence, a subject his father Edmond Becquerel had been an expert in.
Like his father, Henri was especially interested in uranium and its compounds. He was also skilled in photography. In early the scientific community was fascinated with the recent discovery of a new type of radiation. Wilhelm Conrad Roentgen had found that the Crookes tubes he had been using to study cathode rays emitted a new kind of invisible ray that was capable of penetrating through black paper.
Becquerel thought that the phosphorescent uranium salts he had been studying might absorb sunlight and reemit it as x-rays. To test this idea which turned out to be wrong , Becquerel wrapped photographic plates in black paper so that sunlight could not reach them. He then placed the crystals of uranium salt on top of the wrapped plates, and put the whole setup outside in the sun. When he developed the plates, he saw an outline of the crystals.
He also placed objects such as coins or cut out metal shapes between the crystals and the photographic plate, and found that he could produce outlines of those shapes on the photographic plates. Becquerel took this as evidence that his idea was correct, that the phosphorescent uranium salts absorbed sunlight and emitted a penetrating radiation similar to x-rays.
In , after Bronya finished school, Curie moved to Paris. There, she attended Sorbonne to study physics and mathematics. After years of schooling, Curie began her life and research in Paris. Curie received a commission to conduct research post graduation, and found lab space with Pierre Curie, a friend of a colleague. He was also a professor at Sorbonne. The Curies were married two years later.
At the start of their relationship, Pierre and Marie worked on separate project, but after the birth of their first child, Pierre began to conduct research with Marie on x-rays and uranium. Curie was studying uranium rays, when she made the claim the rays were not dependent on the uranium's form, but on its atomic structure.
Her theory created a new field of study, atomic physics, and Marie herself coined the phrase "radioactivity. Marie and Pierre spent time working with pitchblende. Pitchblende is a mineral that is the crystallized form of uranium oxide, and is about 70 percent uranium. Also used in in the discovery of uranium. Marie and Pierre discovered not only polonium, but also radium, through their work with pitchblende.
In , Marie Curie and her husband won the Nobel Prize in physics for their work on radioactivity. If you look up the meaning in the dictionary the convoluted answer that you will receive is: Radioactive - adjective: emitting or relating to the emission of ionizing radiation or particles.
This definition begs the questions: What are ionizing radiation or particles? What exactly is meant by emission? Can you see or feel these particles? What makes something radioactive? Contribution: Received the first Noble Prize in physics for his discovery of x-rays in On November 8, , at the University of Wurzburg, Roentgen was working in the lab when he noticed a strange fluorescence coming from a nearby table. Upon further observation he found that it originated from a partially evacuated Hittof-Crookes tube, covered in opaque black paper which he was using to study cathode rays.
He concluded that the fluorescence, which penetrated the opaque black paper, must have been caused by rays. This phenomenon was later coined x-rays and though the phenomenon of x-rays is not the same as radioactivity, Roentgen opened the door for radioactive discovery.
Contributions: Received the Noble Prize in physics for being the first to discover radioactivity as a phenomenon separate from that of x-rays and document the differences between the two. Henri Becquerel learned of Roentgen's discovery of x-rays through the fluorescence that some materials produce. Using a method similar to that of Roentgen, Becquerel surrounded several photographic plates with black paper and florescent salts. With the intention of further advancing the study of x-rays, Becquerel intended to place the concealed photographic paper in the sunlight and observe what transpired.
Unfortunately, he had to delay his experiment because the skies over Paris were overcast. He placed the wrapped plates into a dark desk drawer. After a few days Becquerel returned to his experiment unwrapping the photographic paper and developing it, expecting only a light imprint from the salts.
Instead, the salts left very distinct outlines in the photographic paper suggesting that the salts, regardless of lacking an energy source, continually fluoresced. What Becquerel had discovered was radioactivity. Contributions: Pierre and Marie were award the Noble Prize in Physics in for their work on radioactivity.
Marie Curie became the first woman to be awarded the nobel prize and the first person to obtain two nobel prizes when she won the prize for the discovery of Polonium and Radium in Though it was Henri Becquerel that discovered radioactivity, it was Marie Curie who coined the term.
Using a device invented by her husband and his brother, that measured extremely low electrical currents, Curie was able to note that uranium electrified the air around it. Further investigation showed that the activity of uranium compounds depended upon the amount of uranium present and that radioactivity was not a result of the interactions between molecules, but rather came from the atom itself.
Using Pitchblende and chalcolite Curie found that Thorium was radioactive as well. She later discovered two new radioactive elements: Radium and Polonium which took her several years since these elements are difficult to extract and extremely rare. Unfortunately, the Curies died young. Pierre Curie was killed in a street accident and Marie died of aplastic anemia, almost certainly a result of radiation exposure. Contributions: Ernest Rutherford is considered the father of nuclear physics.
With his gold foil experiment he was able to unlock the mysteries of the atomic structure. He received the noble prize in chemistry in In at the University of Manchester, Rutherford was bombarding a piece of gold foil with Alpha particles. Rutherford noted that although most of the particles went straight through the foil, one in every eight thousand was deflected back.
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