Radium
Radium
This article is about the chemical element. For other uses, see Radium (disambiguation).
Radium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) on exposure to air, forming a dull purple to blackish surface layer of radium nitride (Ra3N2). All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1600 years and decays into radon gas (specifically the isotope radon-222). When radium decays, ionizing radiation is a product, which can excite fluorescent chemicals and cause radioluminescence.
Radium, 88Ra
General properties
Pronunciation
/ˈreɪdiəm/ (RAY-dee-əm)
Appearance silvery white metallic
Mass number 226 (most stable isotope)
Radium 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
Ba
↑
Ra
↓
(Ubn)
francium ← radium → actinium
Atomic number (Z) 88
Group, period group 2 (alkaline earth metals), period 7
Block s-block
Element category alkaline earth metal
Electron configuration [Rn] 7s2
Electrons per shell
2, 8, 18, 32, 18, 8, 2
Physical properties
Phase (at STP) solid
Melting point 973 K (700 °C, 1292 °F) (disputed)
Boiling point 2010 K (1737 °C, 3159 °F)
Density (near r.t.) 5.5 g/cm3
Heat of fusion 8.5 kJ/mol
Heat of vaporization 113 kJ/mol
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 819 906 1037 1209 1446 1799
Atomic properties
Oxidation states 2 (expected to have a strongly basic oxide)
Electronegativity Pauling scale: 0.9
Ionization energies
1st: 509.3 kJ/mol
2nd: 979.0 kJ/mol
Covalent radius 221±2 pm
Van der Waals radius 283 pm
Spectral lines
Miscellanea
Crystal structure body-centered cubic (bcc)
Thermal conductivity 18.6 W/(m·K)
Electrical resistivity 1 µΩ·m (at 20 °C)
Magnetic ordering nonmagnetic
CAS Number 7440-14-4
History
Discovery Pierre and Marie Curie (1898)
First isolation Marie Curie (1910)
Main isotopes of radium
Isotope Abundance Half-life (t1/2) Decay mode Product
223Ra trace 11.43 d α 219Rn
224Ra trace 3.6319 d α 220Rn
225Ra trace 14.9 d β− 225Ac
226Ra trace 1600 y α 222Rn
228Ra trace 5.75 y β− 228Ac
view talk edit | references | in Wikidata
Radium, in the form of radium chloride, was discovered by Marie and Pierre Curie in 1898. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.[1]
This article is about the chemical element. For other uses, see Radium (disambiguation).
Radium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) on exposure to air, forming a dull purple to blackish surface layer of radium nitride (Ra3N2). All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1600 years and decays into radon gas (specifically the isotope radon-222). When radium decays, ionizing radiation is a product, which can excite fluorescent chemicals and cause radioluminescence.
Radium, 88Ra
General properties
Pronunciation
/ˈreɪdiəm/ (RAY-dee-əm)
Appearance silvery white metallic
Mass number 226 (most stable isotope)
Radium 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
Ba
↑
Ra
↓
(Ubn)
francium ← radium → actinium
Atomic number (Z) 88
Group, period group 2 (alkaline earth metals), period 7
Block s-block
Element category alkaline earth metal
Electron configuration [Rn] 7s2
Electrons per shell
2, 8, 18, 32, 18, 8, 2
Physical properties
Phase (at STP) solid
Melting point 973 K (700 °C, 1292 °F) (disputed)
Boiling point 2010 K (1737 °C, 3159 °F)
Density (near r.t.) 5.5 g/cm3
Heat of fusion 8.5 kJ/mol
Heat of vaporization 113 kJ/mol
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 819 906 1037 1209 1446 1799
Atomic properties
Oxidation states 2 (expected to have a strongly basic oxide)
Electronegativity Pauling scale: 0.9
Ionization energies
1st: 509.3 kJ/mol
2nd: 979.0 kJ/mol
Covalent radius 221±2 pm
Van der Waals radius 283 pm
Spectral lines
Miscellanea
Crystal structure body-centered cubic (bcc)
Thermal conductivity 18.6 W/(m·K)
Electrical resistivity 1 µΩ·m (at 20 °C)
Magnetic ordering nonmagnetic
CAS Number 7440-14-4
History
Discovery Pierre and Marie Curie (1898)
First isolation Marie Curie (1910)
Main isotopes of radium
Isotope Abundance Half-life (t1/2) Decay mode Product
223Ra trace 11.43 d α 219Rn
224Ra trace 3.6319 d α 220Rn
225Ra trace 14.9 d β− 225Ac
226Ra trace 1600 y α 222Rn
228Ra trace 5.75 y β− 228Ac
view talk edit | references | in Wikidata
Radium, in the form of radium chloride, was discovered by Marie and Pierre Curie in 1898. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later. Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.[1]
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