MARIE CURIE AND RADIOACTIVITY

  

Radioactivity is the property that atoms of certain elements have to spontaneously emit ionizing radiation. Radiation can simply be defined as energy, examples of radiation are: light, heat and radio waves. The term ionizing also indicates that this type of radiation is able to destroy the bonds inside the molecules, in fact damaging them.

Examples of ionizing radiation are very high frequency electromagnetic waves such as gamma rays and x-rays, or fragments of heavy atomic nuclei.

Just the heaviest atomic nuclei rich in neutrons can emit the most dangerous radiation for organisms, this is because when ionizing radiation hits a living being, it causes great damage to cells and the DNA contained in them

  The discovery of radioactivity

In March 1896, the physicist French Henri Becquerel, discovered that some photographic x-ray plates kept in the dark, in the presence of a mineral containing uranium, were blackened, as if they had been exposed to light. The ore must therefore have emitted the radiation necessary to impress the x-ray plate.

Two years later, his French-Polish student Marie Curie with her husband Pierre, studying the radiation emitted by pitchblende, a mineral very rich in uranium, discovered the existence of two new elements even more radioactive: Polonium (named in honor of Marie's homeland) and Radium. 

 

Who was Marie Curie?

 

Marie Curie was born in Warsaw in 1867 and distinguished herself throughout her school years for her excellent results. In those years in Poland women were not allowed to enter university studies, so Marie decided to move with one of her sisters to Paris to study at the Sorbonne.

 It was precisely at the university that she met her future husband and "laboratory partner" Pierre whom she married in 1895. Even without collaborators, the Curie spouses began to study the phenomenon they named radioactivity.

Their experiments focused particularly on the uranium-rich Pitchblende mineral, because they noticed that the samples they studied were more radioactive than they should have been, based on the amount of uranium they contained. They therefore hypothesized that in addition to the uranium in these minerals there must be another element more radioactive than the uranium itself, and they began a long work to try to isolate it.

Finally in 1898 they discovered the existence of Polonium. But something still doesn't add up: the samples are still too radioactive, and the mere presence of polonium and uranium does not explain the phenomenon. There is only one possibility: the existence of another element. Thus, on March 28, 1902, Marie Curie announced the discovery of another element, a million times more radioactive than uranium: radium.

Her studies on radiation earned the Curie spouses and the physicist Henri Becquerel the Nobel Prize for physics in 1903, and in 1911 Marie won the second Nobel Prize for the discovery of radium and polonium, historically becoming the only woman among the four winners of two Nobels, and the only one to have won the Prize in two distinct scientific fields.

  

 Affected by aplastic anemia, due to long exposures to radioactive substances, Marie Curie died on July 4, 1934. Even today, all her laboratory notes are considered dangerous due to the radiation they still release. They are stored in special lead-lined boxes and whoever wishes to consult them must wear protective clothing.

 Radioactivity at the time of its discovery was considered a magical fluid by most, greatly increasing the commercial value of radium. In those years toothpastes, beauty creams, pills and drinks containing radium were even advertised and put on the market, responsible for incalculable damage to health. Soon, however, we realized the enormous damage that radiation could cause on healthy individuals. In fact, due to radiation, DNA and cells are damaged and the effects are: burns, dermatitis, leukemia, tumors. DNA damage also causes damage to the children of people who take large doses of radioactivity.

Today we know the double face of radioactivity: we know in fact that the same physical process underlying the functioning of the terrifying nuclear devices can help in the fight against fearful diseases, and if tamed and slowed down in nuclear power plants, it allows energy to be produced for entire cities.

 Some uses of radioactivity

 -Radiopharmaceuticals

By discovering artificial radioactivity, the scientist in fact laid the foundations for the industrial production of radiopharmaceuticals and all the radioactive tracers currently used both in nuclear medicine for the diagnosis of tumors, also with the use of the new Positron Emission Tomography equipment (PET), both in radiometabolic therapy for the targeted treatment of some forms of cancer (such as thyroid) and bone metastases.Thanks to this, radiotherapy was developed.

 -Geology

In fact it is possible to date a wooden object or a fabric with a certain precision, determining the amount of carbon 14 they contain. The method is based on the fact that the half-life of carbon14 is known (5,730 years), that its concentration in the atmosphere, hydrosphere and biosphere is assumed to be constant, that the number of particles emitted by a substance in a given time interval is proportional to the number of carbon atoms14.

 -Industry

It is used to sterilize medical materials, foods and containers that contain it. It can also be used for processing fabrics, non-stick cookware, radioactive tracers for motor oils, eliminating toxic gasses such as sulfur dioxide and nitrogen oxides, etc.

 

                                                                                                                                  Alessia F. , 5scB