Polonium

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Attribution: LIFE, eds. MATTER. LIFE Science Library

Animated Polonium

History

Named after Poland, native country of Madam Curie. Polonium, also called Radium F, was the first element discovered by Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth.

Sources

Polonium is a very rare natural element. Uranium ores contain only about 100 micrograms of the element per ton. Its abundance is only about 0.2% of that of radium.

In 1934, scientists discovered that when they bombarded natural bismuth (209Bi) with neutrons, 210Bi, the parent of polonium, was obtained. Milligram amounts of polonium may now be prepared this way, by using the high neutron fluxes of nuclear reactors.

Uses

Because almost all alpha radiation is stopped within the solid source and its container, giving up its energy, polonium has attracted attention for uses as a lightweight heat source for thermoelectric power in space satellites.

Polonium can be mixed or alloyed with beryllium to provide a source of neutrons. The element has been used in devices for eliminating static charges in textile mills, etc.; however, beta sources are both more commonly used and less dangerous. It is also used on brushes for removing dust from photographic films. The polonium for these is carefully sealed and controlled, minimizing hazards to the user.

Isotopes

Twenty five isotopes of polonium are known, with atomic masses ranging from 194 to 218. Polonium-210 is the most readily available. Isotopes of mass 209 (half-life 103 years) and mass 208 (half-life 2.9 years) can be prepared by alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron, but these are expensive to produce.

Metallic polonium has been prepared from polonium hydroxide and some other polonium compounds in the presence of concentrated aqueous or anhydrous liquid ammonia. Two allotropic modifications are known to exist.

General Info

AtomicNumber
84
Symbol
Po
Name
Polonium

Atomic Info

Appearance
AtomicWeight
[209]
Color
AB5C00
ElectronicConfiguration
[Xe] 4f14 5d10 6s2 6p4
ElectronegativityInPauling
2
AtomicRadiusInPM
IonRadiusInPM
94 (+4)
VanDerWaalsRadiusInPM
IEinKJmol
812
EAinKJmol
-183
OxidationStates
-2, 2, 4, 6
StandardState
solid
BondingType
metallic
MeltingPoint
527
BoilingPoint
1235
Density
9.2
State
Post-transition metal
DiscoveredYear
1898