Silicon-27

Properties and data of the isotope ²⁷Si.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Silicon-27 is a radioisotope of the chemical element silicon, which has 13 neutrons in its atomic nucleus in addition to the element-specific 14 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 27. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁷Si is exclusively for academic purposes.

Silicon-27 was discovered - according to a report from 1939 - by irradiating aluminium-27 (natural Al) with protons (charge exchange reaction):

²⁷Al(p,n)²⁷Si.

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

General data

Name of the isotope:Silicon-27; Si-27Symbol:²⁷Si or 2714SiMass number A:27 (= number of nucleons)Atomic number Z:14 (= number of protons)Neutrons N:13Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):0.92857142857143 (= neutron-proton ratio)Neutron excess (N-Z):-1Isotopic mass:26.98670469(12) u (atomic weight of Silicon-27)Nuclide mass:26.9790247 u (calculated nuclear mass without electrons)Mass excess:-12.3845 MeVMass defect:0.235489666 u (per nucleus)Nuclear binding energy:219.35721094 MeV (per nucleus)
8.12434115 MeV (average binding energy per nucleon)Separation energy:S_N = 13.31482(15) MeV (first neutron)
S_P = 7.46334(13) MeV (first proton)Half-life:4.117(14) sDecay constant λ:0.16836220076754 s^-1Specific activity α:3.899618801965 × 10⁺²¹ Bq g^-1
105395102755.83 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = 0.8652(3)Quadrupole moment Q:+ 0.063(14) barn (100 fm²)Nuclear g-factor:g_l = 0.34608Mirror nucleus:Aluminium-27Year of discovery:1939

Radioactive Decay

Half-life T_½ = 4.117(14) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	²⁷Al	100 %	4.81236(12) MeV

Parent Nuclides

Direct parent isotopes are: ²⁷P, ²⁸S.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 13) and isobaric (same nucleon number A = 27) with Silicon-27. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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

External data and identifiers

Adopted Levels, Gammas:NuDat 27Si

Literature and References

[1] - G. Kuerti, S. N. van Voorhis:
Induced Radioactivity Produced by Bombarding Aluminum with Protons.
In: Physical Review, 56, 614, (1939), DOI 10.1103/PhysRev.56.614.