Pierre was more than a husband to Marie. He was also a partner in her scientific research. The first joint effort was for her thesis paper for Sorbonne. For her paper, she decided that she wanted to find out if the “radioactivity” found by Becquerel in uranium, was found in other materials. Becquerel had stumbled upon radioactivity when he put some uranium and photographic plates in a dark drawer and later found that the plates had been exposed to light which had been emitted by the uranium.
Marie thought that one mineral that would have this radioactivity was pitchblende. Pitchblende is an oxide of uranium ore and it is made up of thirty different elements. Through testing, she determined that it was radioactive, more so than pure uranium. She knew that pitchblende contained many different elements, but she also knew that these known elements were not radioactive. Therefore, she felt that this could only be caused by the presence of other substances in the pitchblende, so she decided to isolate these substances.
This is a sample of pitchblende.
Together the Curies set out to separate the pitchblende through different chemical procedures. They started by putting samples of pitchblende through a chemical analysis which would separate it into a few parts. Some of these parts were more radioactive than others, so she focused on these parts. It proved difficult to isolate the new element that they knew must be in the pitchblende for they didn’t know its characteristic properties or its chemical properties. To overcome this, they decided to begin by separating out the elements that they knew about. This took years to separate all of the known elements from the mineral.
By doing this, the Curies found two new elements, polonium and radium. They also helped to discover a third element, actinium, but this discovery was credited to Becquerel. They had isolated some pure polonium, but they didn’t have any pure radium, so while Pierre investigated the physical properties of polonium, Marie worked on isolating pure radium.
In 1903, they both received the Nobel Prize in physics for their work, sharing it with Becquerel. Later, Pierre died while crossing a street on a rainy day. After Pierre’s death, Marie kept up their work alone. She finally succeeded by crystallizing the chloride of radioactive barium out of a solution which had crystals in it which were more radioactive than other parts of the solution. Because these parts had more radiation, they had more radium in it to produce the radioactive rays. They had to use this crystallization many times to get a pure piece of radium. After isolating it, she observed it properties, finding that its atomic mass was 225. Through all this, she had found a source of light and heat that didn’t required an extra source of energy. It does absorb heat from the area around it sometimes, but it usually uses a store of energy kept inside to give off heat. Marie made many other observations about radium which earned her another Nobel Prize for chemistry in 1911.
After researching some of the properties of the elements that she had helped to discover, she worked to set up institutes that would research radium in more depth. She firmly believed that radium could help to alleviate suffering in the world. During World War I, she tried to us X-rays to locate bullets and to help with surgery of wounded soldiers. Because it isn’t good to move people who are in serious conditions, she organized X-ray vans which could drive around and help the wounded French soldiers.
Marie died in 1934 from leukemia which she had gotten from her exposure to the high levels of radiation which she used in her research. After she died, her ashes were moved to the Pantheon in Paris which is recognized as a high honor.
Marie dedicated her life to her research and should be remembered as a great scientist for all of her contributions to chemistry. Without her, chemistry, particularly the periodic table, would not be the same as it is today.
