Silicon-25

Properties and data of the isotope ²⁵Si.

Contents

Silicon-25 is a radioisotope of the chemical element silicon, which has 11 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 25. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁵Si is exclusively for academic purposes.

The discovery of the proton-rich nuclide was reported in 1963 [1].

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

General data

Name of the isotope:Silicon-25; Si-25Symbol:²⁵Si or 2514SiMass number A:25 (= number of nucleons)Atomic number Z:14 (= number of protons)Neutrons N:11Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):0.78571428571429 (= neutron-proton ratio)Neutron excess (N-Z):-3Isotopic mass:25.004109(11) u (atomic weight of Silicon-25)Nuclide mass:24.996429 u (calculated nuclear mass without electrons)Mass excess:3.82751 MeVMass defect:0.200755524 u (per nucleus)Nuclear binding energy:187.00256607 MeV (per nucleus)
7.48010264 MeV (average binding energy per nucleon)Separation energy:S_N = 14.989(22) MeV (first neutron)
S_P = 3.413(10) MeV (first proton)Half-life:220.6(10) msDecay constant λ:3.142099639891 s^-1Specific activity α:7.568866650951 × 10⁺²² Bq g^-1
2045639635392.4 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Mirror nucleus:Sodium-25Year of discovery:1963

Radioactive Decay

Half-life T_½ = 220.6(10) ms respectively 2.206 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	²⁵Al	65(2) %	12.743(10) MeV
β⁺, p	²⁴Mg	35(2) %	10.469 MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 11) and isobaric (same nucleon number A = 25) with Silicon-25. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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