Atomic Number: 112
Group: 12 or II B
Atomic Weight: 285
Period: 7
CAS Number: 54084-26-3


Noble Gas
Rare Earth Element
Platinum Group Metal
No Stable Isotopes
Solid (Predicted)

Description • Uses/Function

In late February 1996, Siguard Hofmann and his collaborators at GSI Darmstadt announced their discovery of Element 112, having 112 protons and 165 neutrons, with an atomic mass of 277. This element was made by bombarding a lead target with high-energy zinc ions. A single nucleus of Element 112 was detected, which decayed after less than 0.001 sec by emitting an a particle, consisting of two protons and two neutrons. This created Element 110-273, which in turn decayed by emitting an alpha particle to form a new isotope of Element 108 and so on. Evidence indicates that nuclei with 162 neutrons are held together more strongly than nuclei with a smaller or larger number of neutrons. This suggests a narrow “peninsula” of relatively stable isotopes around Element 114. GSI scientists are experimenting to bombard targets with ions heavier than zinc to produce Elements 113 and 114. A name has not yet been suggested for Element 112, although the IUPAC suggested the temproary name of ununbium when the element was discovered. 1

Physical Properties

Density:   g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration: [Rn] 7s2 5f14 6d10
Block: d
Highest Occupied Energy Level: 7
Valence Electrons: 

Quantum Numbers:

n = 6
ℓ = 2
m = 2
ms = -½



Specific Heat: 
Thermal Conductivity:  (W/m)/K, 27°C 2
Heat of Fusion: 
Heat of Vaporization: 
State of Matter Enthalpy of Formation (ΔHf°)3 Entropy (S°)3 Gibbs Free Energy (ΔGf°)3
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(g) 104.0 435.136 48.41 202.54744 96.8 405.0112


Nuclide Mass 4 Half-Life 4 Nuclear Spin 4 Binding Energy
277Cn 277.16394(14)# 1.1(7) ms [0.69(+69-24) ms] 3/2+# 1,999.09 MeV
278Cn 278.16431(57)# 10# ms 0+ 2,007.16 MeV
279Cn 279.16655(53)# 0.1# s 2,015.23 MeV
280Cn 280.16704(69)# 1# s 0+ 2,023.30 MeV
281Cn 281.16929(106)# 10# s 3/2+# 2,031.38 MeV
282Cn 282.16977(76)# 30# s 0+ 2,039.45 MeV
283Cn 283.17179(83)# 4.2(2.1) min 2,038.20 MeV
284Cn 284.17238(91)# 31(18) s 0+ 2,046.27 MeV
285Cn 285.17411(78)# 40(30) min 5/2+# 2,054.35 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 4


Safety Information

Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:


(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:11.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(4) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(5) - Atomic Mass Data Center. (accessed July 14, 2009).