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97 Bk (247)

Berkelium

Actinide
Symbol Bk
Atomic Number 97
Atomic Weight (247)
CAS Registry ID 7440-40-6
Group Name Actinoid
Period Number 7
Block f-block
State at STP Solid

Description

Sample of Berkelium ⌕ Enlarge Image

Berkelium is a synthetic element that is in the actinide family. It is not known what its appearance is, but it is assumed to be a silver, white, or metallic solid, and it is assumed to be a solid; not much is known about the element, but it is also predicted that it will oxidize in air at increased temperatures. Berkelium has an atomic weight of 247, a melting point of 1807 ° F, and its boiling point is not known. There are currently no commercial uses of berkelium.

Isolation

Berkelium is not found in nature at all and must be synthesized using special equipment and processes. It is a radioactive metal and must be treated with caution.

Berkelium ⌕ Enlarge Image

Currently berkelium is synthesized by bombarding the element americium with alpha particles. It was the fifth element of its kind to be synthesized, and it was first synthesized in 1949; at that time, berkelium was synthesized and isolated using an isotope, number 241, of americium. The americium isotope was bombarded with alpha particles which produced an isotope of berkelium, number 243, that had a half life of 4.5 hours. Alpha particles are formed from two protons and two neutrons that closely resemble the nucleus of the element helium. Alpha particles are created by radioactive nuclei from elements such as uranium or radium during the process of alpha decay. Different chemical forms of berkelium have been identified using x-ray diffraction; some of these forms included berkelium oxychloride, berkelium fluoride, berkelium dioxide, and berkelium trioxide. Some predicted isotopes of berkelium have half lives that could last up to 1380 years, but the majority of the isotopes of this element have half lives of less than 5 hours. The shortened half life makes isolation procedures especially difficult.

General

NameBerkelium
SymbolBk
Number97
Chemical seriesActinide
Groupn/a
Period7
Blockf
Appearanceunknown
Standard atomic weight(247) g·mol⁻¹
Electron configuration[Rn] 5f9 7s2
Electrons per shell2, 8, 18, 32, 27, 8, 2

Atomic Properties

Crystal structurehexagonal close-packed
Oxidation states3, 4
Electronegativity1.3 (scale Pauling)
Ionization energies1st: 601 kJ/mol
Atomic radius
Atomic radius (calc.)
Covalent radius
Van der Waals radius

Physical Properties

Phasesolid
Density (near r.t.)(alpha) 14.78  g·cm−3
Liquid density at m.p.
Melting point(beta) 1259 K (986 °C, 1807 °F)
Boiling point
Critical point
Heat of fusion
Heat of vaporization
Heat capacity

Miscellaneous

Magnetic ordering
Electrical resistivity
Thermal conductivity(300 K) 10  W·m−1·K−1
Thermal expansion
Speed of sound (thin rod)
Young's modulus
Shear modulus
Bulk modulus
Poisson ratio
Mohs hardness
Vickers hardness
Brinell hardness