Argon-45

Properties and data of the isotope ⁴⁵Ar.

Content

General data

Name of the isotope:Argon-45; Ar-45Symbol:⁴⁵Ar or 4518ArMass number A:45 (= number of nucleons)Atomic number Z:18 (= number of protons)Neutrons N:27Isotopic mass:44.9680397(6) u (atomic weight of Argon-45)Nuclide mass:44.9581654 u (calculated nuclear mass without electrons)Mass excess:-29.77083 MeVMass defect:0.406763608 u (per nucleus)Nuclear binding energy:378.89786027 MeV (per nucleus)
8.41995245 MeV (average binding energy per nucleon)Separation energy:S_N = 5.1689(17) MeV (first neutron)
S_P = 16.68(14) MeV (first proton)Half-life:21.48(15) sDecay constant λ:0.032269421813778 s^-1Specific activity α:4.416613718892 × 10⁺²⁰ Bq g^-1
11936793834.845 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-.7/2-Year of discovery:1974

Radioactive Decay

Half-life T_½ = 21.48(15) s respectively 2.148 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁴⁵K	100 %	6.8448(7) MeV

Parent Nuclides

Direct parent isotopes are: ⁴⁵Cl, ⁴⁶Cl.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 27) and isobaric (same nucleon number A = 45) with Argon-45. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

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