Polonium

Polonium, ₈₄Po

File:Polonium.jpg
Polonium
Pronunciation	/pəˈloʊniəm/ (listenⓘ) ​(pə-LOH-nee-əm)
Allotropes	α, β
Appearance	silvery
Mass number	[209]
Polonium 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 Te ↑ Po ↓ Lv bismuth ← polonium → astatine
Atomic number (Z)	84
Group	group 16 (chalcogens)
Period	period 6
Block	p-block
Electron configuration	[Xe] 4f14 5d10 6s2 6p4
Electrons per shell	2, 8, 18, 32, 18, 6
Physical properties
Phase at STP	solid
Melting point	527 K ​(254 °C, ​489 °F)
Boiling point	1235 K ​(962 °C, ​1764 °F)
Density (near r.t.)	α-Po: 9.196 g/cm3 β-Po: 9.398 g/cm3
Heat of fusion	ca. 13 kJ/mol
Heat of vaporization	102.91 kJ/mol
Molar heat capacity	26.4 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) (846) 1003 1236
Atomic properties
Oxidation states	−2, +2, +4, +5, +6 (an amphoteric oxide)
Electronegativity	Pauling scale: 2.0
Ionization energies	1st: 812.1 kJ/mol
Atomic radius	empirical: 168 pm
Covalent radius	140±4 pm
Van der Waals radius	197 pm
Spectral lines of polonium
Other properties
Natural occurrence	from decay
Crystal structure	​cubic α-Po
Crystal structure	​rhombohedral β-Po
Thermal expansion	23.5 µm/(m⋅K) (at 25 °C)
Thermal conductivity	20 W/(m⋅K) (?)
Electrical resistivity	α-Po: 0.40 µΩ⋅m (at 0 °C)
Magnetic ordering	nonmagnetic
CAS Number	7440-08-6
History
Naming	after Polonia, Latin for Poland, homeland of Marie Curie
Discovery	Pierre and Marie Curie (1898)
First isolation	Willy Marckwald (1902)
Isotopes of polonium
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 208Po synth 2.898 y α 204Pb β+ 208Bi 209Po synth 125.2 y α 205Pb β+ 209Bi 210Po trace 138.376 d α 206Pb

Polonium is recognized as one of the most toxic elements on the periodic table.

Polonium is a rare radioactive metalloid. It is chemical element 84 on the periodic table and its symbol is Po. It was discovered in 1898 by Marie and Pierre Curie.

Polonium is highly unstable, radioactive and toxic. This makes it difficult to handle. It can be dangerous, even in very small amounts. One gram of Po will self-heat to a temperature of about 500 °C (932 °F). It also vaporizes easily.

Polonium has 42 isotopes, and all of them are radioactive. It is a very rare element in nature because of its short half-life. It is a breakdown product of uranium, so it is found in uranium ores.

Polonium is also very important because it is the main element of nuclear bombs.

Polonium emits alpha radiation, which cannot pass through the skin and is blocked by a piece of paper.

Properties

Polonium emits alpha radiation, and it has a half-life of 138 days (approximately 4 months). It decays into Lead, A milligram of polonium emits about as many alpha particles per second as 5 grams of Radium, which means it is 5,000 times more radioactive than radium. A few grams of Polonium emit a blue glow which is caused by ionization of the surrounding air. Polonium is 100 billion times more dangerous than hydrogen cyanide.

Polonium has an atomic number of 84, meaning it has 84 protons, which is why it's so unstable, because it's atom is large.