Actinium facts for kids

Quick facts for kids
Actinium, ₈₉Ac

Actinium
Pronunciation	/ækˈtɪniəm/ ​(ak-TIN-ee-əm)
Appearance	silvery-white
Mass number	227
Actinium 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 La ↑ Ac ↓ (Uqu) radium ← actinium → thorium
Atomic number (Z)	89
Group	group 3
Period	period 7
Block	d
Electron configuration	[Rn] 6d1 7s2
Electrons per shell	2, 8, 18, 32, 18, 9, 2
Physical properties
Phase at STP	solid
Melting point	(circa) 1323 K ​(1050 °C, ​1922 °F)
Boiling point	3471 K ​(3198 °C, ​5788 °F)
Density (near r.t.)	10 g/cm3
Heat of fusion	14 kJ/mol
Heat of vaporization	400 kJ/mol
Molar heat capacity	27.2 J/(mol·K)
Atomic properties
Oxidation states	+2, +3 (a strongly basic oxide)
Electronegativity	Pauling scale: 1.1
Covalent radius	215 pm
Spectral lines of actinium
Other properties
Natural occurrence	from decay
Crystal structure	​face-centered cubic (fcc)
Thermal conductivity	12 W/(m⋅K)
Magnetic ordering	no data
CAS Number	7440-34-8
History
Discovery	André-Louis Debierne (1899)
First isolation	André-Louis Debierne (1899)
Main isotopes of actinium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 225Ac trace 10 d α 5.935 221Fr 226Ac syn 29.37 h β− 1.117 226Th ε 0.640 226Ra α 5.536 222Fr 227Ac trace 21.772 y β− 0.045 227Th α 5.042 223Fr

Actinium is chemical element 89 on the periodic table. Its symbol is Ac. Actinium's mass is 227 g/mol.

Actinium is a silver radioactive, solid metal in actinide group. It is so radioactive that it glows in the dark. Even a small amount of actinium is dangerous to people.

History

Actinium was discovered in 1899 by André-Louis Debierne, a French chemist. In 1899, Debierne described the substance as similar to titanium and (in 1900) as similar to thorium.

Properties

Actinium is a soft, silvery-white, radioactive metal.

Because its strong radioactivity, actinium glows in the dark with a pale blue light.

Actinium reacts quickly with oxygen and moisture in air forming a white coating (actinium oxide) that stops the actinium from oxidizing.

Occurence

Actinium is only found in very tiny amounts in uranium and thorium ores.

Uses

Actinium is now being studied for use in cancer treatments. It can be used in radiation therapy.

Images for kids

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  Uraninite ores have elevated concentrations of actinium.

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  Chemical structure of the DOTA carrier for 225Ac in radiation therapy.

See also

In Spanish: Actinio para niños