Phosphorus-42

Properties and data of the isotope ⁴²P.

Contents

General data

Name of the isotope:Phosphorus-42; P-42Symbol:⁴²P or 4215PMass number A:42 (= number of nucleons)Atomic number Z:15 (= number of protons)Neutrons N:27Isotopic mass:42.00108(34) u (atomic weight of Phosphorus-42)Nuclide mass:41.9928514 u (calculated nuclear mass without electrons)Mass excess:1.00601 MeVMass defect:0.350248212 u (per nucleus)Nuclear binding energy:326.25410799 MeV (per nucleus)
7.76795495 MeV (average binding energy per nucleon)Separation energy:S_N = 2.08(34) MeV (first neutron)
S_P = 18.40(64) MeV (first proton)Half-life:48.5(15) msDecay constant λ:14.291694444535 s^-1Specific activity α:2.049204692194 × 10⁺²³ Bq g^-1
5538391059984.9 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1979

Radioactive Decay

Half-life T_½ = 48.5(15) ms respectively 4.85 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy
β^-	⁴²S	50 %	18.68724 MeV
β^-, n	⁴¹S	50(20) %	12.027 MeV
β^-, 2n	⁴⁰S	?

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 27) and isobaric (same nucleon number A = 42) with Phosphorus-42. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 27	Isobar A = 42
11	³⁸Na
12	³⁹Mg
13	⁴⁰Al	⁴²Al
14	⁴¹Si	⁴²Si
15	⁴²P	⁴²P
16	⁴³S	⁴²S
17	⁴⁴Cl	⁴²Cl
18	⁴⁵Ar	⁴²Ar
19	⁴⁶K	⁴²K
20	⁴⁷Ca	⁴²Ca
21	⁴⁸Sc	⁴²Sc
22	⁴⁹Ti	⁴²Ti
23	⁵⁰V	⁴²V
24	⁵¹Cr	⁴²Cr
25	⁵²Mn	⁴²Mn
26	⁵³Fe
27	⁵⁴Co
28	⁵⁵Ni
29	⁵⁶Cu
30	⁵⁷Zn
31	⁵⁸Ga
32	⁵⁹Ge