{"id":244,"date":"2020-04-09T10:09:19","date_gmt":"2020-04-09T10:09:19","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=244"},"modified":"2023-08-16T11:46:29","modified_gmt":"2023-08-16T11:46:29","slug":"curium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/curium\/","title":{"rendered":"Curium (Cm)"},"content":{"rendered":"

Curium is a radioactive chemical element with the symbol Cm and atomic number 96 in the periodic table of elements<\/a>. This rare-earth element is not found in Earth\u2019s crust due to the fact that it\u2019s a man-made substance. As a member of the family of transuranic elements, this actinide has three and occasionally four valence electrons, which makes curium highly unstable in reactions with other chemical elements.<\/p>\n

Chemical and Physical Properties of Curium<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/strong><\/td>\nValue<\/strong><\/td>\n<\/tr>\n
The symbol in the periodic table of elements<\/td>\nCm<\/td>\n<\/tr>\n
Atomic number<\/td>\n96<\/td>\n<\/tr>\n
Atomic weight (mass)<\/td>\n(247) g.mol -1<\/td>\n<\/tr>\n
Group number<\/td>\nN\/A (Actinides)<\/td>\n<\/tr>\n
Period<\/td>\n7<\/td>\n<\/tr>\n
Color<\/td>\nSilvery<\/td>\n<\/tr>\n
Physical state<\/td>\nSolid metal<\/td>\n<\/tr>\n
Half-life<\/td>\n163 days<\/td>\n<\/tr>\n
Electronegativity according to Pauling<\/td>\n\u03c7 = 1.3<\/td>\n<\/tr>\n
Density<\/td>\n13.51 g.cm-3 at 20\u00b0C<\/td>\n<\/tr>\n
Melting point<\/td>\n1340 \u00b0C<\/td>\n<\/tr>\n
Boiling point<\/td>\nUnknown<\/td>\n<\/tr>\n
Van der Waals radius<\/td>\nUnknown<\/td>\n<\/tr>\n
Ionic radius<\/td>\nUnknown<\/td>\n<\/tr>\n
Isotopes<\/td>\nNo stable isotopes \/ 19 radioisotopes<\/td>\n<\/tr>\n
Most characteristic isotope<\/td>\nCurium-247<\/td>\n<\/tr>\n
Electronic shell<\/td>\n[Rn] 5f7 6d1 7s2<\/td>\n<\/tr>\n
The energy of the first ionization<\/td>\nUnknown<\/td>\n<\/tr>\n
The energy of the second ionization<\/td>\nUnknown<\/td>\n<\/tr>\n
Discovery date<\/td>\nIn 1944\u00a0 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Despite being discovered before americium, curium follows the aforementioned chemical element in the periodic table. With the symbol Cm, atomic number 96, atomic mass of (247) g.mol -1, and electron configuration [Rn] 5f7 6d1 7s2, curium is a hard and brittle metal with a density of 13.51 g.cm-3 at 20\u00b0C. It tarnishes at room temperature when exposed to dry air.<\/p>\n

The atomic radius and the boiling point of this insoluble member of the actinides are unknown. Regarding the melting point, it’s achieved at 1340 \u00b0C, which is higher than the transuranic elements neptunium<\/a> (637 \u00b0C), plutonium (639 \u00b0C), and americium (1173 \u00b0C) that come before curium in the periodic table.<\/p>\n

Curium reacts mostly with oxygen<\/a> and assumes a +3 oxidation state as its most stable result of the reaction with oxygen. Due to the high spontaneous fission rate of this radioactive substance, it acts as a strong source of radiation. The analysis of the crystal structure of curium shows resemblance to the crystals of the other actinides: americium<\/a>, berkelium<\/a>, and californium<\/a>.<\/p>\n

How Was Curium Discovered?<\/h2>\n

In 1944, a group of scientists working at the University of California, Berkeley, attempted to secretly synthesize a new radioactive element. One day in July, the American chemists Glenn Seaborg, Ralph A. James, and Albert Ghiorso, conducted an experiment at a wartime Metallurgical Laboratory at the University of Chicago, U.S.<\/p>\n

The group of scientists bombarded plutonium<\/a> Pu-239 with helium<\/a>-ion alpha particles in a 60-inch cyclotron. This strictly confidential chemical trial resulted in the discovery of a new radioactive chemical element in its pure elemental form – curium-242 and one free neutron.<\/p>\n

However, this great discovery wasn\u2019t announced immediately as World War II was still raging. After the war, the new chemical element was introduced to the world in November 1947. The same year, the American nuclear chemists Louis Werner and Isadore Perlman attempted to bombard americium-241 with neutrons in order to produce more significant quantities of this radioactive actinide.<\/p>\n

The metallic form of this man-made chemical element was obtained in 1951 by W. W. T. Crane, J. C. Wallmann. and B. B. Cunningham.<\/p>\n

How Did Curium Get Its Name?<\/h2>\n

This radioactive chemical element was named in honor of Marie and Pierre Curie, both recognized as pioneers of radioactivity.<\/p>\n

Where Can You Find Curium?<\/h2>\n

Apart from being produced in laboratories by neutron capture reactions of plutonium and americium isotopes, curium can be found in the used nuclear fuel of nuclear power plants, as well as in locations where nuclear testings are conducted.<\/p>\n

Curium in Everyday Life<\/h2>\n

This radioactive and insufficiently studied chemical element doesn\u2019t have wide use in everyday life. However, there are many significant applications of curium in space technologies, power generation industries, radiology, and scientific researches:<\/p>\n