A chemical element. Chemical symbol Ra, atomic number 88, atomic weight 226.0254, belongs to IIA group in the periodic table, is a member of alkaline earth metal and a natural radioactive element. 1898 m. Curie and p. Curie separated radium bromide from the slag after extracting uranium from pitchblende, and 19 10 made metal radium by electrolysis of radium chloride. Its English name comes from the Latin radius, which means "ray". The content of radium in the crust is 1× 10-9%. It has been found that isotopes with mass numbers of 206 ~ 230 are all artificially synthesized except for radium 223, radium 224, radium 226 and radium 228, which are natural radioactive isotopes. Radium exists in all uranium mines, and every 2.8 tons of uranium contains 1 gram of radium.
Radium is a silvery white metal with a melting point of 700℃, a boiling point lower than 1 140℃ and a density of about 5g/cm3. Radium is the most active alkaline earth metal, which reacts rapidly with nitrogen and oxygen in air to form nitrides and oxides, and reacts violently with water to form radium hydroxide and hydrogen. The outermost electron shell of radium has two electrons, and the oxidation state is +2, and only +2 valence compounds are formed. Radium salts and corresponding barium salts are isomorphic compounds with similar chemical properties. Radium chloride, radium bromide and radium nitrate are all soluble in water, while radium sulfate, radium carbonate and radium chromate are insoluble in water. Radium is highly toxic and can be concentrated in bones instead of calcium in human body. Acute poisoning can cause bone marrow damage and serious damage to hematopoietic tissue, while chronic poisoning can cause osteoma and leukemia. Radium is a by-product of uranium production. When leaching uranium from uranium ore with sulfuric acid, radium exists in slag in the form of sulfate, and then it is converted into radium chloride. Pure radium salt can be obtained by fractional crystallization with barium salt as carrier. Metal radium is made from electrolytic radium chloride. Radium and its decay products emit gamma rays, which can destroy malignant tissues in the human body, so radium needles can cure cancer.
Element Name: Radium
Atomic weight of element: [226]
Element type: metal
Discovers: Marie Curie and pierre curie: 1898.
Discovery process:
1898 was discovered by Marie Curie and pierre curie. 19 10, Madame Curie and Debin electrolyzed pure radium chloride solution, used mercury as cathode to obtain radium amalgam, and then distilled off mercury to obtain metal radium.
Element description:
The density is 6.0g/cm3 (20℃). The melting point is 700℃ and the boiling point is about 1 140℃. Silvery white smooth soft metal. It is unstable in air, easy to combine with nitrogen and easy to oxidize in air. It reacts with water to release hydrogen and generate radium hydroxide Ra(OH)2. Soluble in dilute acid. Chemical properties are very similar to barium; All radium salts are isomorphic to the corresponding barium salts. Radium can generate sulfate, carbonate, chromate and iodate which are only slightly soluble in water; Chlorides, bromides and hydroxides of radium are soluble in water. Radium is known to have 13 isotope, and 226Ra has the longest half-life of 1622 years.
Element source:
It exists in many kinds of ores and mineral springs, but its content is extremely rare, and more of it comes from pitchblende. When uranium is extracted from pitchblende, radium is usually recovered and purified together with barium in the form of sulfate in acid-insoluble residue.
Element usage:
Radium can emit alpha and gamma rays and produce radioactive gas radon. Radium can destroy and kill cells and bacteria. Therefore, it is often used to treat cancer. In addition, the mixed preparation of radium salt and beryllium powder can be used as neutron radiation source to detect petroleum resources and rock composition.
Element auxiliary data:
Shortly after the discovery of polonium, the Curies had another amazing result. After they separated bismuth compounds rich in polonium from uranium mines, they also separated barium compounds with strong radioactivity. They believe that this mineral also contains a second unknown radioactive element, which was separated from barium at the same time. Their collaborator Belmont successfully studied this unknown radioactive element. 1898 In February, the Paris Academy of Sciences published a report on their cooperation with Beaumont: "... The above reasons make us believe that this new radioactive substance contains a new element, and we suggest calling it radium. ……"
Radium, the Latin name of radium, comes from the Latin word "radius", and its element symbol is defined as ra.
The content of radium in pitchblende is very small, but it is only one in ten million or three in ten million. To separate it, a lot of pitchblende is needed. From 1898 to 1902, a huge amount (one ton) of slag was painstakingly analyzed in a simple laboratory, and finally 0. 1g of metal radium was extracted from 1902, and its atomic weight was preliminarily determined.
The discovery of radium
After Becker's pioneering observation and research on the radioactivity of uranium, he found that uranium rays, like X rays, can make air and other gases conduct electricity, and thorium compounds were also found to have similar properties.
Starting from 1896, Madame Curie and her husband made a systematic discovery, looking for this effect in various elements and their compounds and natural objects.
Mabya Sklodowska Ya, a famous Madame Curie, was born in a scholarly family in Warsaw, Poland on17. My father is everyone's physics professor and my mother is a pianist. Maria, with her father's wisdom and mother's dexterity, has been interested in scientific experiments since she was a child.
189 1 year, she went to Paris to study. After finishing her studies, she originally planned to return to her motherland, which was ravaged by the czar, to make a modest contribution to the motherland, and to do her daughter's filial piety for her parents.
However, the acquaintance, love and lifelong companionship with French physicist Mr. pierre curie completely changed her original plan, so she had to live in France and gave birth to a lovely daughter on 1897.
Becquerel phenomenon aroused the strong interest of Curie and his wife. Where does the power of ray release come from? What is the nature of this radiation?
Madame Curie devoted herself to the study of uranium salts. She collects and studies all kinds of uranium salts and ores extensively. She was attracted by the magical light of uranium salt ore, and she devoted special love to this special ore.
Madame Curie, who received a strict and systematic higher chemistry education, thought that there was no reason to prove that uranium was the only chemical element that could emit radiation when studying uranium salt ores. She guessed that there must be other elements with the same power, but people just didn't know it yet.
She determined the elements one by one according to Mendeleev's periodic law of elements. As a result, she soon discovered another thorium compound, which also automatically emits rays, similar to uranium rays and close in intensity.
Madame Curie realized that this phenomenon is not just the characteristics of uranium, and it must be given a new name. Madame Curie named it "radioactive", and uranium, thorium and other substances with this special "radiation" function are called "radioactive elements".
Later, with the help of her husband, Mr. Pierre, she measured all the minerals she could collect. She wants to know what other minerals are radioactive.
In the measurement, she made another dramatic discovery. In a pitchblende mine in Czechoslovakia at that time, she found that its radioactive intensity was many times greater than originally thought.
So, where did this abnormal and excessive radioactivity come from? The contents of uranium and needles in these pitchblende can never explain the radioactive intensity she observed.
Therefore, there can only be one explanation. These asphaltene minerals contain a new element that is much more radioactive than uranium and needles, and it is not known to mankind at that time. It must be an unknown element.
Madame Curie's discovery caught Mr Pierre's attention, and the Curie couple went hand in hand and launched a powerful attack on the unknown scientific field.
In the extremely harsh laboratory, through the persistent long-term efforts of the Curie couple,1July, 898, they announced the discovery of this new element, which is 400 times more radioactive than pure uranium.
To commemorate her tortured motherland Poland, the new element was named polonium (meaning Poland).
1898 65438+In February, the Curies announced that they had discovered a second radioactive element, which was more radioactive than polonium. They named this new element.
"Radium".
However, because there were no samples and atomic weights of polonium and radium, almost no one in the scientific community at that time wanted to believe their shocking new discovery.
The Curies are determined to extract samples of polonium and radium at any cost, on the one hand, to confirm their existence, and on the other hand, to make themselves more certain.
Of course, this is a very difficult thing.
Because pitchblende containing polonium and radium is an expensive mineral, it mainly exists in the San Joachimsthal mine in Bohemia. By melting this mineral, people can extract uranium salts to make colored glass.
The Curies are a pair of intellectuals with considerable economic resources, and they are unable to pay the high cost of purchasing pitchblende. But they are not intimidated by this "obstacle" in front of them, and almost all methods have been tried.
After many twists and turns, the Austrian government officially decided to donate a ton of slag to the Curie couple first, and promised that if they needed a lot of slag in the future, they could supply it to them on the most favorable terms.
The curies breathed a long sigh of relief. They borrowed money from their friends and raised a sum of money because they had to buy this raw material and pay the freight to Paris.
They are once again caught in a long wait.
One morning, just as the sun rose, a heavy carriage like a coal truck stopped at the door of the Curie couple's house.
Madame Curie was so happy that the pitchblende she had been waiting for day and night finally came, and her dream radium was hidden here!
She quickly cut the rope with a knife, tore open the coarse cloth pocket, and deeply inserted a pair of slender hands into the brown mineral, from which she had to extract radium.
Madame Curie immediately threw herself into the heavy extraction work. She put more than 20 kilograms of waste residue into a smelting pot for heating and melting, stirred the boiling slag liquid continuously for several hours with a thick iron bar, and then extracted only one millionth of trace substances from it.
From 1898 to 1902, after countless times of extraction, dozens of tons of slag were treated, and finally 0. 1 g radium salt was obtained, and its atomic weight was determined to be 225.
Radium was finally born!
The discovery of radium triggered a real revolution in the scientific community. 1903, the curies both won the nobel prize in physics. Madame Curie's great success is by no means easy. It embodies the sweat and tears of Madame Curie, which is the crystallization of Madame Curie's painstaking efforts.