Phosphorus-33

Properties and data of the isotope ³³P.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Phosphorus-33 is a radioisotope of the chemical element phosphorus, which has 18 neutrons in its atomic nucleus in addition to the element-specific 15 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 33. The short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ³³P is exclusively for academic purposes.

A report on the discovery of the nuclide appeared in 1951 [1]. According to this report, phosphorus-33 could be produced and detected by irradiating elemental sulfur, sodium sulfide, and lithium chloride with gamma rays of an energy of 48 MeV; the isotope was formed by the following photonuclear reactions:

³⁴S(γ,p)³³P,

³⁵Cl(γ,2p)³³P,

³⁷Cl(γ,α)³³P.

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

General data

Name of the isotope:Phosphorus-33; P-33Symbol:³³P or 3315PMass number A:33 (= number of nucleons)Atomic number Z:15 (= number of protons)Neutrons N:18Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.2 (= neutron-proton ratio)Neutron excess (N-Z):3Isotopic mass:32.9717257(12) u (atomic weight of Phosphorus-33)Nuclide mass:32.9634971 u (calculated nuclear mass without electrons)Mass excess:-26.33734 MeVMass defect:0.30161826800001 u (per nucleus)Nuclear binding energy:280.95560693 MeV (per nucleus)
8.51380627 MeV (average binding energy per nucleon)Separation energy:S_N = 10.1038(11) MeV (first neutron)
S_P = 9.5486(11) MeV (first proton)Half-life:25.38(6) dDecay constant λ:3.160968011046 × 10^-7 s^-1Specific activity α:5.948685817586 × 10⁺¹⁵ Bq g^-1
160775.29236721 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+Mirror nucleus:Argon-33Year of discovery:1951

Radioactive Decay

Half-life T_½ = 25.38(6) d respectively 2.192832 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	³³S	100 %	0.2485(11) MeV

Parent Nuclides

Direct parent isotope is: ³³Si.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 18) and isobaric (same nucleon number A = 33) with Phosphorus-33. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 18	Isobar A = 33
7	²⁵N
8	²⁶O
9	²⁷F
10	²⁸Ne	³³Ne
11	²⁹Na	³³Na
12	³⁰Mg	³³Mg
13	³¹Al	³³Al
14	³²Si	³³Si
15	³³P	³³P
16	³⁴S	³³S
17	³⁵Cl	³³Cl
18	³⁶Ar	³³Ar
19	³⁷K	³³K
20	³⁸Ca
21	³⁹Sc
22	⁴⁰Ti
23	⁴¹V
24	⁴²Cr
25	⁴³Mn

External data and identifiers

Adopted Levels, Gammas:NuDat 33P

Literature and References

[1] - Raymond K. Sheline, Richard B. Holtzman, Chang-Yun Fan:
The Nuclide P³³ and the P³² Spectrum.
In: Physical Review, 83, 919, (1951), DOI 10.1103/PhysRev.83.919.