Radioactive elements are part of the natural balance system

OF: DEVELOPMENTS group Zhao Yuliang CHAI aryl radioactive means capable of spontaneously emits the particles or radiation (e.g., α particles, beta] rays, gamma] rays, etc.) from the inside of the unstable nucleus, while the release of energy, forming an earth elements stable nuclides, which A process is called radioactive decay. Elements with an atomic number above 84 are all radioactive, and certain elements with atomic number below 83 such as cesium (Tc), *(Pm), etc. are also radioactive.

Radioactive elements are divided into natural radioactive elements and artificial radioactive elements. Natural radioactive elements include *(Po), Ru, Ru, Fr, Ac, Th, Pa, and *(U); synthetic radioactive elements , such as elements in the lanthanide element after *. There are three major natural radiation systems in the natural world: the *, 锕 and 钍 series. The ancestors of these three series are 238U, 235U and 232Th, respectively.

In the long period after the birth of modern chemistry, radioactivity was not known. The discovery of radioactive elements was actually earlier than the discovery of radioactivity. In 1789, German chemist Claprot discovered*. In 1828 the Swedish chemist Besselius discovered the cricket. But at the time, * and 钍 were only seen as general heavy metal elements. Until the German physicist Roentgen discovered X-rays in 1895, many scientists were eager to study this new type of radiation with great penetrating power. Radioactivity was discovered. In 1896 the French physicist Becquerel discovered the radioactivity of *.

After Madame Curie discovered * and radium from the Asphalt mine samples in 1898, people realized that it was a radioactive element and other radioactive elements were discovered one after another. In 1899, the French scientist Debbie Elne isolated radioactive elements from slag - 锕. In 1900, the German physicist Donn pointed out that when radium decays, it will generate a gaseous element. The radioactive gas was a fresh thing at the time. This element was later named as helium and was listed as element 86; finally, by 1917, two research groups - the Hahn and Metternich group in Germany, the United Kingdom Sodexo and Cranston's team - again separated from the bitumen * ore No. 9l - element. In 1937, the Italian physicists Perrier and Segre discovered the No. 43 element helium using a cyclotron to bombard molybdenum with a helium nucleus. It is the first radioactive element made by artificial means.

Natural radioactive elements constitute an integral part of the earth and nature. In all types of rocks, soils, rivers, lakes, and the atmosphere, there are different amounts of radioactive elements. One of them accounts for one thousandth of the average Clarke value in the earth's crust. Radioactive elements are increasingly used in many areas such as nuclear power plants, space technology, medical technology, and isotope technology to serve humans. Naturally occurring low concentrations of radioactive radiation are generally not harmful to human health and are already part of the natural balance system. Humans and other lives have adapted to the background radiation environment of this balanced system during the course of evolution.