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The elements of the periodic table are many and each one of them has different characteristics (from the other-deleted). There are metals, semi-metals, non metals, transitions elements… the aspects of chemistry are various and most of them un-explored. We can either talk about the condition of the elements, solid, liquid or gas; or about the ebullition or the fusion temperatures, the electro negativity of the elements and radioactivity. Now we have to formulate a logical question:
What is the radioactivity?
The radioactivity is the capacity of the atoms to emit different kinds of radiation, a radiation, b radiation and g radiation (the most dangerous). Depending on the stability of the nucleon of the atom, the higher the number of protons is, the more unstable the atom becomes. Protons are the positive particles, electrons the negative ones and neutrons are neutron particles, with the function of stabilization, because positive charges always repel other positive charges. Almost each atom of the periodic table has isotopes (atoms with the same atomic number but different mass number), and part of them are radioactive. There are also natural elements like uranium, or as we are going to talk about, radium and polonium, that have as natural property the radioactivity. During the centuries radioactive atoms lost part of their particles in order to reach more stability in the nucleon. Some disciplines use the decay of the atoms to date the existence of a particular organism, or even the dating of the life of a particular animal species.
The radiation emitted by the radioactive atoms normally isn’t very dangerous, a and b radiation are constituted by positive and negatives particles, protons and electrons, and could penetrate slight layers of metals like Aluminum. g radiations could penetrate thick layers of Lead or other metals, and are constituted by photons. In our presentation we now pass to the second question:
Who discovered radioactivity as a feature of some elements?
We owe the discovery of radioactivity to a brave and intelligent woman, Marie Curie.
Marie Sklodowska-Curie was born in Warsaw, the 7th November 1867, in Poland. Fifth daughter of a Mathematics and Physics teacher, she studied for some years as self-taught, because girls couldn’t attend university in Poland. Her passions were Mathematics and Physics, and at first her family didn’t approve her choice. On 1891 Marie’s older sister went to Paris to attend the famous Sorbonne university, to (take degrees as and) become a doctor. In order to pay the expenses of the University, Marie started to work as a governess, and she had been working for six years, when her sister Bronya graduated. During those six years, Bronya had already got married and found a house where she and her husband lived. Bronya repaid the favor to her sister, paying her university expenses and giving her hospitality for some time.
Marie studied Physics at the university in the morning, and Mathematics and Chemistry in the evening as self-taught. Here, in Paris, she met a brilliant scientist, Pierre Curie, and they married on the 26th of July 1895. Pierre was a Physics teacher at the Sorbonne University, and he had made research about the magnetic properties and quartz piezo-electric properties with his brother Jacques. Thanks to his studies, Marie could start her research about the radioactivity, and soon they became also laboratory mates.
After two years of marriage, they have their first daughter Irène, and on 1904 their second daughter, Eve, is born.
Marie wanted to study a particular characteristic of some elements, what now we call radioactivity and started to study this phenomena in a little house in Rue Lohmond, where the couple created a laboratory. Their research studied at first the radioactivity of Uranium’s salt (discovered many years before by Henry Becquerel) in different kind of substances, pure or not. They measured the radioactivity with a particular piezo-electric electrode made-up of quartz, reporting different measures depending on the concentration of Uranium. The properties of those piezo-electric electrodes had been studied by Pierre several years before, but Pierre’s old studies were concentrated only on magnetic properties (in 1882 Pierre with his brother Jacques registered their discovery about the properties of the quartz). Thanks to Pierre’s knowledge they continued their research for many years, examining, reporting data and formulating theories and more others. Then they tried to measure the radioactivity in other elements, observing their reactions and properties.
Marie and Pierre formulated a definition of the radioactivity, and said that the radioactivity is a characteristic of the atom, not a feature of the substance as all the scientists thought at that time.
After months of study they tried to measure the radioactivity of a substance named “pitchblende”, a radioactive material coming from mines in the south of the France. At that time the scientists thought that this substance was constituted by Uranium. They discovered that the radioactivity of this substance was much more intense than the normal radioactivity of Uranium, in consequence they understood that the substance wasn’t pure Uranium, but a mixture of more substances, possibly more radioactive than Uranium. They tried to divide this substance with more and more experiments, extracting Uranium and dividing the remnants in order to finally obtain a new element with characteristics different from any other in the periodic table. Marie and Pierre called this element “Polonium”.
They published their discoveries in a journal named “Swatlo” and named the new element for the first time.
The Polonium had a radioactivity more intense than Uranium and this justified a certain level of radioactivity, but it wasn’t so high to justify the level of radioactivity of the pitchblende, so they tried for the second time to divide the elements, and discover a little quantitative of a new substance, much more radioactive than the Polonium, the Radium.
In order to reach their goal, Marie and Pierre analyzed tons of pitchblende, absorbing a huge quantitative of radiation that eventually took Marie to death after many years and risking her life for the research.
Marie and Pierre could have earned millions and become very reach if only they had registered their discovery, but they didn’t, in order to make possible for everyone to study this particular topic and take the science to another level, developing the technology of that period.
Officially they announced their discoveries the 26th December 1898, and in 1903, Marie and Pierre with a scientist named Henry Becquerel, received the Nobel Prize for Physics.
In 1906 Pierre died in a car accident and Marie took his place as a teacher at the Sorbonne University, becoming the first woman to teach here.
Even after Pierre’s death, Marie continued her research, trying to create pure Polonium and pure Radium; after many years she isolated pure metallic Radium and Polonium, and won in 1911 the second Nobel Prize, this time for Chemistry.
Marie Curie published different papers about her research the most popular being: “Researches sur les substances Radioactives” (1904); “L’isotopie et les elements Isotopes”; “Traité de la radioactivité” (1910). She also wrote different papers that explained how to extract pure Polonium and pure Radium.
She has founded a particular institute, at first named “Istitute du radium”, which is still known nowadays as “Istitute Curie”. Irène, Marie’s first daughter, had the same attitude as her mother and soon she started to study Physics and Chemistry with her mother’s encouragement.
Marie’s and Pierre’s research wasn’t applied only in Physics and Chemistry, it made a several progress about the fight against the cancer and most of the congenital illnesses, and also they had an important role in the development of X-Rays. During the World War I Marie worked as radiologist with her daughter Irène saving millions of lives. They worked with the Red Cross Association and with them they invented the first car with X-Rays equipment, and with this Marie and Irène went personally near the lines of fight.
In 1920 Marie became very fragile, and fourteen years later she died of pernicious anemia in the sanatorium of Sancellemoz, an illness caused from the huge amount of radiation absorbed during her research.
Personally I admire this woman, She fought against the prejudice and studied at the university, even if her parents didn’t approve. She persisted in her research, working hard and obtaining very important results and she continued even after the loss of her husband, working alone and at the same time raising her daughters, Irène and Eve, that became after her death very important people- Irène won a Nobel prize for Chemistry as her mother had done, and Eve worked as ambassador for UNICEF. During her last year of life Marie worked as a radiologist, near the conflict of the World War I, saving lots of lives and risking hers. She died because of her research, the radiation caused that illness and even now she rests in her final and last sleep in a lead coffin, near her husband, because her body continues to emit radiation. Her original scripts are preserved in a special place, because of the radiation, and most of her objects are preserved in the same way.
I think that everyone should know what Marie Curie has done in her incredible life, because for me she represents an ideal of what all the scientists should be, altruist and brave.
We can easily say that Marie Curie’s case is one when pure intellect meets bravery.