Isotopes of phosphorus

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Although phosphorus (P) has 23 isotopes from 24P to 46P, only one of these isotopes is stable 31P; as such, it is considered a monoisotopic element. The longest-lived radioactive isotopes are 33P with a half-life of 25.34 days and 32P with a half-life of 14.263 days. All other have half-lives under 2.5 minutes, most under a second. The least stable is 25P with a half-life shorter than 30 nanoseconds—the half-life of 24P is unknown.

Standard atomic mass: 30.973762(2) u

Radioactive isotopes of phosphorus include:

  • 32P; a beta-emitter (1.71 MeV) with a half-life of 14.3 days which is used routinely in life-science laboratories, primarily to produce radiolabeled DNA and RNA probe, e.g. for use in Northern blots or Southern blots. Because the high energy beta particles produced penetrate skin and corneas, and because any 32P ingested, inhaled, or absorbed is readily incorporated into bone and nucleic acids, OSHA requires that a lab coat, disposable gloves, and safety glasses or goggles be worn when working with 32P, and that working directly over an open container be avoided in order to protect the eyes.[citation needed] Monitoring personal, clothing, and surface contamination is also required. In addition, due to the high energy of the beta particles, shielding this radiation with the normally used dense materials (e.g. lead), gives rise to secondary emission of X-rays via a process known as Bremsstrahlung, meaning braking radiation. Therefore shielding must be accomplished with low density materials, e.g. Plexiglas, Lucite, plastic, wood, or water.
  • 33P; a beta-emitter (0.25 MeV) with a half-life of 25.4 days. It is used in life-science laboratories in applications in which lower energy beta emissions are advantageous such as DNA sequencing. Phosphorus-33 can be used to label nucleotides. It is less energetic than 32P, giving a better resolution. A disadvantage is its higher cost compared to 32P, as most of the bombarded 31P will have acquired only one neutron, while only some will have acquired two or more. Its maximum specific activity is 5118 Ci/mol.

Table[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[1]
daughter
isotope(s)[n 1]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
24P 15 9 24.03435(54)# ? p (>99.9%) 23Si (1+)#
β+ (<.1%) 24Si
25P 15 10 25.02026(21)# <30 ns p 24Si (1/2+)#
26P[n 2] 15 11 26.01178(21)# 43.7(6) ms β+ (98.1%) 26Si (3+)
β+, 2p (1.0%) 24Mg
β+, p (.9%) 25Al
27P 15 12 26.999230(28) 260(80) ms β+ (99.93%) 27Si 1/2+
β+, p (.07%) 26Al
28P 15 13 27.992315(4) 270.3(5) ms β+ (99.99%) 28Si 3+
β+, p (.0013%) 27Al
β+, α (8.6×10−4%) 24Mg
29P 15 14 28.9818006(6) 4.142(15) s β+ 29Si 1/2+
30P 15 15 29.9783138(3) 2.498(4) min β+ 30Si 1+
31P 15 16 30.97376163(20) Stable 1/2+ 1.0000
32P 15 17 31.97390727(20) 14.263(3) d β- 32S 1+ trace
33P 15 18 32.9717255(12) 25.34(12) d β- 33S 1/2+
34P 15 19 33.973636(5) 12.43(8) s β- 34S 1+
35P 15 20 34.9733141(20) 47.3(7) s β- 35S 1/2+
36P 15 21 35.978260(14) 5.6(3) s β- 36S 4-#
37P 15 22 36.97961(4) 2.31(13) s β- 37S 1/2+#
38P 15 23 37.98416(11) 0.64(14) s β- (88%) 38S
β-, n (12%) 37S
39P 15 24 38.98618(11) 190(50) ms β- (74%) 39S 1/2+#
β-, n (26%) 38S
40P 15 25 39.99130(15) 153(8) ms β- (70%) 40S (2-,3-)
β-, n (30%) 39S
41P 15 26 40.99434(23) 100(5) ms β- (70%) 41S 1/2+#
β-, n (30%) 40S
42P 15 27 42.00101(48) 48.5(15) ms β- (50%) 42S
β-, n (50%) 41S
43P 15 28 43.00619(104) 36.5(15) ms β-, n 42S 1/2+#
44P 15 29 44.01299(75)# 18.5(25) ms β- 44S
45P 15 30 45.01922(86)# 8# ms [>200 ns] β- 45S 1/2+#
46P 15 31 46.02738(97)# 4# ms [>200 ns] β- 46S
  1. ^ Bold for stable isotopes
  2. ^ Has 1 halo proton

Notes[edit]

  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References[edit]

External links[edit]

  1. ^ http://www.nucleonica.net/unc.aspx


Isotopes of silicon Isotopes of phosphorus Isotopes of sulfur
Table of nuclides