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Argon-40

Properties and data of the isotope 40Ar.


Content

See also: list of Argon isotopes.

 

General data

Name of the isotope:Argon-40; Ar-40Symbol:40Ar or 4018ArMass number A:40 (= number of nucleons)Atomic number Z:18 (= number of protons)Neutrons N:22Isotopic mass:39.96238312(2) u (atomic weight of Argon-40)Nuclide mass:39.9525088 u (calculated nuclear mass without electrons)Mass excess:-35.0399 MeVMass defect:0.369095608 u (per nucleus)Nuclear binding energy:343.81034428 MeV (per nucleus)
8.59525861 MeV (average binding energy per nucleon)
Separation energy:SN = 9.869(5) MeV (first neutron)
SP = 12.2587(17) MeV (first proton)
Half-life:stableSpin and parity:
(nuclear angular momentum)
0+Charge radius:3.4274(26) femtometer fmMirror nucleus:Titanium-40Year of discovery:1920

 

Parent Nuclides

Direct parent isotopes are: 40Cl, 40K.

 

Occurrence

Comparison of the natural Argon isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

 

Atomic Mass maQuantityHalf-lifeSpin
Argon
Isotopic mixture
39.88 u100 %
Isotope 36Ar35.9675451(2) u0.3336(210) %stable0+
Isotope 38Ar37.962732(2) u0.0629(70) %stable0+
Isotope 39Ar38.964313(5) u
[trace]
268(8) a7/2-
Isotope 40Ar39.96238312(2) u99.6035(250) %stable0+
Isotope 42Ar41.963046(6) u
[trace]
32.9(11) a0+

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 22) and isobaric (same nucleon number A = 40) with Argon-40. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 22Isobar A = 40
931F
1032Ne
1133Na
1234Mg40Mg
1335Al40Al
1436Si40Si
1537P40P
1638S40S
1739Cl40Cl
1840Ar40Ar
1941K40K
2042Ca40Ca
2143Sc40Sc
2244Ti40Ti
2345V40V
2446Cr
2547Mn
2648Fe
2749Co
2850Ni

 

External data and identifiers

Adopted Levels, Gammas:NuDat 40Ar

 


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Last update: 2023-10-04


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