Carbon-20

Properties and data of the isotope ²⁰C.

Contents

Carbon-20 is a radioisotope of the chemical element carbon, which has 14 neutrons in its atomic nucleus in addition to the element-specific 6 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 20. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁰C is exclusively for academic purposes.

The first observation of the radioactive isotope was first reported in 1981 in an experiment in which calcium-48 ions accelerated to 213 MeV per nucleon were fragmented on a Be target [1].

See also: List of individual Carbon isotopes (and general data sources).

General data

Name of the isotope:Carbon-20; C-20Symbol:²⁰C or 206CMass number A:20 (= number of nucleons)Atomic number Z:6 (= number of protons)Neutrons N:14Isotopic mass:20.04026(25) u (atomic weight of Carbon-20)Nuclide mass:20.0369685 u (calculated nuclear mass without electrons)Mass excess:37.50195 MeVMass defect:0.127999016 u (per nucleus)Nuclear binding energy:119.23031541 MeV (per nucleus)
5.96151577 MeV (average binding energy per nucleon)Separation energy:S_N = 2.982(251) MeV (first neutron)
S_P = 29.556(574) MeV (first proton)Half-life:16.3 msDecay constant λ:42.524366905518 s^-1Specific activity α:1.280438637423 × 10⁺²⁴ Bq g^-1
34606449660089 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:2.617 femtometer fmMatter radius:3.193 femtometer fmYear of discovery:1981

Radioactive Decay

Half-life T_½ = 16.3 ms respectively 1.63 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	²⁰N	> 11.4 %	15.74(24) MeV
β^-, n	¹⁹N	70(11) %	2.982(251) MeV
β^-, 2n	¹⁸N	< 18.6 %

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 14) and isobaric (same nucleon number A = 20) with Carbon-20. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 14	Isobar A = 20
5	¹⁹B	²⁰B
6	²⁰C	²⁰C
7	²¹N	²⁰N
8	²²O	²⁰O
9	²³F	²⁰F
10	²⁴Ne	²⁰Ne
11	²⁵Na	²⁰Na
12	²⁶Mg	²⁰Mg
13	²⁷Al	²⁰Al
14	²⁸Si
15	²⁹P
16	³⁰S
17	³¹Cl
18	³²Ar
19	³³K
20	³⁴Ca