13 Des 2014

Archimedes & Marie Curie



ARCHIMEDES

Archimedes was a Greek mathematician and philosopher who lived from 287 to 212 B.C. According to legend, he was asked by the emperor to determine whether a crown was made of pure gold or a mixture of gold and less valuable metals, such as silver and copper. After receiving this assignment, Archimedes was taking a bath one day when he noticed that the deeper his body sank into the water, the more water overflowed the bath, and his body seemed to weigh less the more it was submerged. He concluded that the apparent loss of weight of an object submerged in a liquid is equal to the weight of the liquid it displaces. This principle, now named after him.

Having previously observed that the volume of an object determines the volume of the liquid it displaces, he would weigh the crown and the same weight of gold both immersed in water in separate containers. Because every object has a different ratio of weight to volume, or density, the crown (if it was not made entirely of gold) and the pure gold that weighed the same amount in air would have different weights in water because they would displace different volumes of water. Supposedly, Archimedes was so excited by his brilliance that he ran from the bath shouting “Eureka”-the Greek word for “I have found it!”.
Chemistry is largely an experimental science. Like Archimedes’ discovery, most advances in chemistry are the results of observations and experiments, although the setting is usually in a laboratory.


MARIE CURIE

More than a century ago scientists became interested in the radioactivity phenomenon. A young graduate student named Marie Sklodowska Curie, with her husband Pierre Curie as her coworker, chose as the subject of her doctoral research radioactive uranium ore. In 1898 the Curies isolated a new element, which they named polonium after Marie’s native country of Poland. Four months later, they discovered radium, another radioactive element.
In their makeshift laboratory in a shed, Marie and Pierre processed tons of pitchblende (a uranium oxide ore) to obtain just 0.1 g of the fluorescent blue substance at their bedside, and they loved to visit the shed at night to look at the luminous test tubes glowing like fairy lights. The unusual properties of radium made it the most important element to be discovered since oxygen. Marie Curie’s thesis was hailed by many scientists as “the greatest contribution to science ever made by a doctoral student.”

Along with Becquerel (the discoverer of radioactivity), the Curies were awarded the Nobel Prize in Physics in 1903-the same year in which Marie received her doctoral degree. By then, Marie Curie was a household word, the world’s most famous scientists nevertheless encountered hostility and discrimination in the scientist community. She was denied admission to the French Academy of Sciences by one vote because she was a woman!
Marie Curie was the first woman to win a Noble Prize, the first person to win two Nobel Prize (the second in chemistry in 1911), and the first Noble Prize winner to have a child go on to win a Noble Prize. Today the element with the atomic number 96, curium (Cm), is named in Marie Curie’s honor.

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