Roentgenium-278

Properties and data of the isotope ²⁷⁸Rg.

Content

General data

Name of the isotope:Roentgenium-278; Rg-278Symbol:²⁷⁸Rg or 278111RgMass number A:278 (= number of nucleons)Atomic number Z:111 (= number of protons)Neutrons N:167Isotopic mass:278.16159(42) u (atomic weight of Roentgenium-278)Nuclide mass:278.100708 u (calculated nuclear mass without electrons)Mass excess:150.52012 MeVMass defect:2.154029524 u (per nucleus)Nuclear binding energy:2006.46557743 MeV (per nucleus)
7.21750208 MeV (average binding energy per nucleon)Separation energy:S_N = 5.958(609) MeV (first neutron)
S_P = 1.861(552) MeV (first proton)Half-life:0.0042 sDecay constant λ:165.03504299046 s^-1Specific activity α:3.575051351490 × 10⁺²³ Bq g^-1
9662300949973.5 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:2007

Radioactive Decay

Half-life T_½ = 0.0042 s respectively 4.2 × 10^-3 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁷⁴Mt	ca. 100 %	10.846(95) MeV
SZ	div	?

Parent Nuclides

Direct parent isotope is: ²⁸²Nh.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 167) and isobaric (same nucleon number A = 278) with Roentgenium-278. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 167	Isobar A = 278
107	²⁷⁴Bh	²⁷⁸Bh
108	²⁷⁵Hs
109	²⁷⁶Mt	²⁷⁸Mt
110	²⁷⁷Ds	²⁷⁸Ds
111	²⁷⁸Rg	²⁷⁸Rg
112	²⁷⁹Cn	²⁷⁸Cn
113	²⁸⁰Nh	²⁷⁸Nh