Curium

Curium is a synthetic chemical element in the periodic table that has the atomic number 96. It has the chemical symbol Cm and it is a radioactive metal. In chemistry it is placed in a group of metal elements named the actinides. Curium is a transuranic element. It is a radioactive element that does not exist in nature. Curium has a silver color and it is made by bombarding a plutonium target with alpha particles (helium ions). Curium was named after Marie Curie and her husband Pierre.

Curium, ₀₀Cm

Curium
Pronunciation	/ˈkjʊəriəm/ ​(KURE-ee-əm)
Appearance	silvery metallic, glows purple in the dark
Mass number	[247]
Curium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Gd ↑ Cm ↓ (Upn) americium ← curium → berkelium
Group	f-block groups (no number)
Period	period 7
Block	f-block
Electron configuration	[Rn] 5f7 6d1 7s2
Electrons per shell	2, 8, 18, 32, 25, 9, 2
Physical properties
Phase at STP	solid
Melting point	1613 K ​(1340 °C, ​2444 °F)
Boiling point	3383 K ​(3110 °C, ​5630 °F)
Density (near r.t.)	13.51 g/cm3
Heat of fusion	13.85 kJ/mol
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1788 1982
Atomic properties
Oxidation states	+3, +4, +5,[1] +6[2] (an amphoteric oxide)
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 581 kJ/mol
Atomic radius	empirical: 174 pm
Covalent radius	169±3 pm
Spectral lines of curium
Other properties
Natural occurrence	synthetic
Crystal structure	​double hexagonal close-packed (dhcp)
Electrical resistivity	1.25 µΩ⋅m[3]
Magnetic ordering	antiferromagnetic-paramagnetic transition at 52 K[3]
CAS Number	7440-51-9
History
Naming	named after Marie Skłodowska-Curie and Pierre Curie
Discovery	Glenn T. Seaborg, Ralph A. James, Albert Ghiorso (1944)
Isotopes of curium v e
Main isotopes[4] Decay abun­dance half-life (t1/2) mode pro­duct 242Cm synth 162.8 d α 238Pu SF – 34Si ... 243Cm synth 29.1 y α 239Pu ε 243Am SF – 244Cm synth 18.11 y α 240Pu SF – 245Cm synth 8250 y α 241Pu SF – 246Cm synth 4060 y α 242Pu SF – 247Cm synth 1.56×107 y α 243Pu 248Cm synth 3.480×105 y α 244Pu SF – 250Cm synth 8300 y SF – α 246Pu β− 250Bk
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