Phosphorus-40

Properties and data of the isotope ⁴⁰P.

Content

General data

Name of the isotope:Phosphorus-40; P-40Symbol:⁴⁰P or 4015PMass number A:40 (= number of nucleons)Atomic number Z:15 (= number of protons)Neutrons N:25Isotopic mass:39.99129(16) u (atomic weight of Phosphorus-40)Nuclide mass:39.9830614 u (calculated nuclear mass without electrons)Mass excess:-8.11331 MeVMass defect:0.34270838 u (per nucleus)Nuclear binding energy:319.23079972 MeV (per nucleus)
7.98076999 MeV (average binding energy per nucleon)Separation energy:S_N = 3.41(19) MeV (first neutron)
S_P = 17.72(20) MeV (first proton)Half-life:150(8) msDecay constant λ:4.620981203733 s^-1Specific activity α:7.13543582564 × 10⁺²² Bq g^-1
1928496169092.2 Ci g^-1Spin and parity:
(nuclear angular momentum)(2-.3-)Year of discovery:1979

Radioactive Decay

Half-life T_½ = 150(8) ms respectively 1.50 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	⁴⁰S	84.2(21) %	14.85592 MeV
β^-, n	³⁹S	15.8(21) %	7.0166 MeV
β^-, 2n	³⁸S	?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 25) and isobaric (same nucleon number A = 40) with Phosphorus-40. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 25	Isobar A = 40
11	³⁶Na
12	³⁷Mg	⁴⁰Mg
13	³⁸Al	⁴⁰Al
14	³⁹Si	⁴⁰Si
15	⁴⁰P	⁴⁰P
16	⁴¹S	⁴⁰S
17	⁴²Cl	⁴⁰Cl
18	⁴³Ar	⁴⁰Ar
19	⁴⁴K	⁴⁰K
20	⁴⁵Ca	⁴⁰Ca
21	⁴⁶Sc	⁴⁰Sc
22	⁴⁷Ti	⁴⁰Ti
23	⁴⁸V	⁴⁰V
24	⁴⁹Cr
25	⁵⁰Mn
26	⁵¹Fe
27	⁵²Co
28	⁵³Ni
29	⁵⁴Cu
30	⁵⁵Zn