Question

What " S " discovered the element Barkelium ?​

Answer 1

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Berkelium is a transuranic radioactive chemical element with the symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory) where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium.

Berkelium, 97Bk

Berkelium metal.jpg

Berkelium

Pronunciation

/bərˈkɛliəm/

(bər-KEL-ee-əm)

/ˈbɜːrkliəm/

(BUR-klee-əm)

Appearance

silvery

Mass number

[247]

Berkelium 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

Tb

↑

Bk

↓

(Upu)

curium ← berkelium → californium

Atomic number (Z)

97

Group

n/a

Period

period 7

Block

f-block

Electron configuration

[Rn] 5f9 7s2

Electrons per shell

2, 8, 18, 32, 27, 8, 2

Physical properties

Phase at STP

solid

Melting point

beta: 1259 K (986 °C, 1807 °F)

Boiling point

beta: 2900 K (2627 °C, 4760 °F)

Density (near r.t.)

alpha: 14.78 g/cm3

beta: 13.25 g/cm3

Heat of fusion

7.92 kJ/mol (calculated)

Atomic properties

Oxidation states

+2, +3, +4, +5[1]

Electronegativity

Pauling scale: 1.3

Ionization energies

1st: 601 kJ/mol

Atomic radius

empirical: 170 pm

Color lines in a spectral range

Spectral lines of berkelium

Other properties

Natural occurrence

synthetic

Crystal structure

double hexagonal close-packed (dhcp)Double hexagonal close packed crystal structure for berkelium

Thermal conductivity

10 W/(m·K)

Magnetic ordering

paramagnetic

CAS Number

7440-40-6

History

Naming

after Berkeley, California, where it was discovered

Discovery

Lawrence Berkeley National Laboratory (1949)

Main isotopes of berkelium

Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct

245Bk syn 4.94 d ε 245Cm

α 241Am

246Bk syn 1.8 d α 242Am

ε 246Cm

247Bk syn 1380 y α 243Am

248Bk syn >300 y[2] α 244Am

249Bk syn 330 d α 245Am

SF –

β− 249Cf

Category Category: Berkelium

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The major isotope of berkelium, 249Bk, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the Oak Ridge National Laboratory in Tennessee, USA, and at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. The production of the second-most important isotope 247Bk involves the irradiation of the rare isotope 244Cm with high-energy alpha particles.

Just over one gram of berkelium has been produced in the United States since 1967. There is no practical application of berkelium outside scientific research which is mostly directed at the synthesis of heavier transuranic elements and transactinides. A 22 milligram batch of berkelium-249 was prepared during a 250-day irradiation period and then purified for a further 90 days at Oak Ridge in 2009. This sample was used to synthesize the new element tennessine for the first time in 2009 at the Joint Institute for Nuclear Research, Russia, after it was bombarded with calcium-48 ions for 150 days. This was the culmination of the Russia–US collaboration on the synthesis of the heaviest elements on the periodic table.

Berkelium is a soft, silvery-white, radioactive metal. The berkelium-249 isotope emits low-energy electrons and thus is relatively safe to handle. It decays with a half-life of 330 days to californium-249, which is a strong emitter of ionizing alpha particles. This gradual transformation is an important consideration when studying the properties of elemental berkelium and its chemical compounds, since the formation of californium brings not only chemical contamination, but also free-radical effects and self-heating from the emitted alpha particles