What is Radioactivity?
 
Radioactivity is the natural or artificial nuclear phenomenon that results from the emission of particles or energy from the atoms when there is disintegration or some sort of instability with the chemical elements.
Natural Radioactivity is the property that some unstable atoms, such as Uranium and Radio, have to spontaneously emit radiation (particles or energy) in the form of particles and waves, becoming more stable and lighter chemical elements. This can also be called radioactive decay or nuclear disintegration.
Nuclear Stability is a concept that helps to identify the stability of an isotope. To identify the stability of an isotope it is needed to find the ratio of neutrons to protons.  
Nuclear Binding Energy is the energy required to separate an atomic nucleus completely into its constituent protons and neutrons, or, equivalently, the energy that would be liberated by combining individual protons and neutrons into a single nucleus.
 

 
Radioactive Decay Formula
 
The radioactive decay law states that the probability per unit time that a nucleus will decay is a constant, independent of time. This constant is called the decay constant and is denoted by λ, “lambda”. This constant probability may vary greatly between different types of nuclei, leading to the many different observed decay rates. The radioactive decay of certain number of atoms (mass) is exponential in time.
 
Radioactive decay law: N = N0.e-λt

N – number of particles
 
The rate of nuclear decay is also measured in terms of half-lives. The half-life is the amount of time it takes for a given isotope to lose half of its radioactivity.

The radioactive decay law can be derived also for activity calculations (when you want to know the average number of radioactive decays per unit time) or mass of radioactive material calculations:

(Activity) A = A0.e-λt      (Mass) m = m0.e-λt                                                                           
 
A- total activity , m – total mass  
 
 

The Discovery of Radioactivity
 
Radioactivity was originally discovered in 1896 by the French scientist Henri Becquerel, while he was studying the natural phosphorescence* of substances. Becquerel's discovery was only possible thanks to previous studies on X-ray, which  was discovered in 1895, by the German physicist Wilhelm Konrad Röntgen.
He accidentally  discovered a new type of ray, which made it possible to 'see' within the human body.  As the physicist didn’t know exactly what the nature of these rays were, he called them  X-rays.
The discovery of the German physique led Becquerel in early 1896 to test the hypothesis that phosphorescent and fluorescent substances would also emit X-rays.
This accidentally later led Becquerel together with the Curies to discover that Uranium emitted rays of radioactivity.
 
* (phosphorescence is a process in which energy absorbed by a substance is released relatively slowly in the form of light)
 

 

The Pitchblende
 
After Becquerel's discovery, Marie and Pierre Curie proved the existence of other radioactive substances, finding a high level of radioactivity in Thorium.
When analyzing pitchblende (Uranium ore), Marie Curie detected more radioactive intensity in pitchblende than that observed in uranium and assumed that these minerals contained some radioactive chemical element not yet discovered.
For three years, the Curie couple worked extensively until 1902, where they were able to isolate two other chemical elements (unknown at the time) of the pitchblende.

 

Radium
 
One of those two chemical elements discovered was called Radium, which is 2 million times more radioactive than Uranium.

 

 

Polonium
 
The Curies also extracted an element 400 times more radioactive than uranium, which as a tribute to Marie Curie's homeland, they called Polonium.  
 
 
 
Alpha, Beta and Gamma Rays
 
The radiations emitted by radioactive substances are called Alpha rays, Beta rays and Gamma rays. Marie and Pierre Curie were among those responsible for their identification.  
Alpha rays have a positive electrical charge. They consist of two protons and two neutrons, these emissions being identical to the core of Helium's atoms. It also has a very high mass and electric charge and is very energetic. Alpha radiation is also the one with the least penetrating power amongst the three.
Beta rays have a negative electrical charge. Beta particles are less energetic than Alpha particles but have more penetrating power.
Gamma rays, absent of electric charge, are not as energetic as Alpha nor Beta rays, but they are extremely penetrating and these can endanger human health.
 

 
Who was Marie Curie?
 
Marie Curie was born in Poland on November 7, 1867. She was the youngest of five children. On both the paternal and maternal sides, the family had lost their property and fortunes through patriotic involvements in Polish national uprisings aimed at restoring Poland's independence. This condemned the subsequent generation, including Marie and her elder siblings, to a difficult struggle to get ahead in life. Both of her parents were professors, and her mother taught Mathematics and Physics, subjects that Maria was to pursue.
Even though the only university in Warsaw was a men's only school, she managed to discover an underground university for women, where she studied physics.
Her mother was a devoted catholic but since her mother and sister early death’s, Marie Curie became agnostic.
In 1891, she went to Paris to continue her studies at the Sorbonne where she obtained Licentiateships in Physics and Mathematical Sciences. There, she met Pierre Curie, professor in the school of Physics. In 1895 they got married.
 
 

Marie Curie Nobel Prizes
 
Marie Curie was not only the first women to win a Nobel prize she was also the first person to win the Nobel prize twice.
Until this day, she is still the only person that won the Nobel Prize from different categories..
Henri Becquerel discovery of radioactivity took Marie and Pierre to extract from the pitchblende, two unknown elements, polonium and radium as we said before both more radioactive than uranium, because of that, in 1903, Marie together with her husband and Henri Becquerel won the Physics Nobel Prize.
In 1906 Pierre Curie died in a road accident, but that didn't stop Marie. She continued to investigate radium and polonium properties. In 1910, she successfully produced radium as a pure metal, which proved the new element's existence beyond a doubt.
She also documented the properties of the radioactive elements and their compounds. Radioactive compounds became important as sources of radiation in both scientific experiments and in the field of medicine. And in 1911 Marie won the Chemistry Nobel Prize because of the previous researches.
 
 
 
Petite Curie
 
In 1914, three German bombs collided in Paris and Germany declared war on France. By that time construction of the Radium Institute was complete, although Curie had not yet moved her lab there. Curie's researchers had been drafted. The Radium Institute's work would have to wait. Marie decided to help.  
 
“I am resolved to put all my strength at the service of my adopted country, since I cannot do anything for my unfortunate native country just now...”  - Marie Curie to Paul Langevin, January 1, 1915

Marie couldn’t do anything to help Poland but could save lives in France and that’s what she did. She realized that with x-rays she could  help doctors to see bullets, and broken bones. By that time she had never work with x-rays before so she learned by herself and with that she had an idea the Petite Curie.
The Petite Curie was a car that came with a generator, a hospital bed, and an X-ray machine.
With them, she was able to detect the presence of bullets in soldiers who came to the van to be X-rayed, making the work of the surgeons on the front lines easier because they knew where to operate. She helped in frontline until the end of the war.
 
 
 
The Radium Institute
 
When the war ended ,1919, The central task of her life was no longer her own research, but directing the Radium Institute. Seeing that science was becoming specialized, she organized the Radium Institute in a new way, an entire major laboratory devoted to a single subject radioactivity. Marie loved all of her staff; she considered the staff like her children's
The Radium Institute used materials from a lot of countries they actually used salts obtained from the uranium ore from the Barracão mine (Guarda, Portugal).

Under Marie Curie direction the Radium Institute in Paris became a world center for the study of radioactivity.
The Radium Institute published 483 works, including 31 papers and books by Curie herself.
She worked there until the end of her life in 1934 due to overexposure to radiation. Marie unfortunately didn’t saw her daughter winning the Nobel Prize since she won in 1935 but we know that she would be proud of it.
 
 
 
The Legacy
 
Marie Curie ashes are since 1995 in the Pantheon of Paris as a symbol for women.
Marie Curie is for sure a pioneer who helped pave the way for women in science. She had been through a lot of discrimination but she proved them that a woman can also be a scientist, even the French media was trying to sabotage her when they discovered her affair with the physician Paul Langevin.
Marie Curie was also the first woman to be on the Solvay Conference a conference with the best scientist in the world at the time. She is remembered until this day as the most important woman of all time.
One century later we still use Marie Curie discovery's.
Radioisotopes are used in medicine and In research until this day. The nuclei of radioisotopes are unstable. In an attempt to reach a more stable arrangement of its neutrons and protons, the unstable nucleus will spontaneously decay to form a different nucleus. If the number of neutrons changes in the process (number of protons remains), a different isotopes is formed and an element remains (e.g. neutron emission). If the number of protons changes (different atomic number) in the process, then an atom of a different element is formed. This decomposition of the nucleus is referred to as radioactive decay. During radioactive decay an unstable nucleus spontaneously and randomly decomposes to form a different nucleus (or a different energy state – gamma decay), giving off radiation in the form of atomic particles or high energy rays. This decay occurs at a constant, predictable rate that is referred to as half-life. A stable nucleus will not undergo this kind of decay and is thus non-radioactive.

 

Radioisotopes - Application in Research



 

 

 

 

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Radiopharmaceuticals can be used to diagnosis or as therapeutic agents.
 
Radiotherapy, is a therapy using ionizing radiation, generally as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor.   
Around 5 million people per year survive to cancer due to Radiotherapy.
 
Even tough Marie Curie died in 1934, if wasn’t her previous researches and discovery's millions of people would die from cancer today, she is really an inspiration for everybody.

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Conclusion

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To finish our project we want to express the amount of respect that we have towards Madame Curie. She is a true warrior, a simple woman from Poland that gave her life to Science, fought against all odds to became the first person ever to win two noble prizes, all of this being a woman in the 20th century. A person that everyone should admire and know more of we hope that with this project the person who is reading this became a more cultured person.