Potassium-40m

Properties and data of the isotope ⁴⁰K.

Content

General data

Name of the isotope:Potassium-40m; K-40mSymbol:⁴⁰K or 4019KMass number A:40 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:21Isotopic mass:39.9639982(4) u (atomic weight of Potassium-40m)
Excitation energy: 1643.638(11) keVNuclide mass:39.9535754 u (calculated nuclear mass without electrons)Mass excess:-33.53546 MeVMass defect:0.366640644 u (per nucleus)Nuclear binding energy:341.52356004 MeV (per nucleus)
8.538089 MeV (average binding energy per nucleon)Half-life:0.336(13) μsDecay constant λ:2062938.0373808 s^-1Specific activity α:3.185462422161 × 10⁺²⁸ Bq g^-1
8.60935789773 × 10⁺¹⁷ Ci g^-1Spin and parity:
(nuclear angular momentum)0+

Radioactive Decay

Half-life T_½ = 0.336(13) μs respectively 3.36 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	⁴⁰K

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
⁴⁰K		1.248(3) × 10⁹ a	4-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 21) and isobaric (same nucleon number A = 40) with Potassium-40m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 21	Isobar A = 40
9	³⁰F
10	³¹Ne
11	³²Na
12	³³Mg	⁴⁰Mg
13	³⁴Al	⁴⁰Al
14	³⁵Si	⁴⁰Si
15	³⁶P	⁴⁰P
16	³⁷S	⁴⁰S
17	³⁸Cl	⁴⁰Cl
18	³⁹Ar	⁴⁰Ar
19	⁴⁰K	⁴⁰K
20	⁴¹Ca	⁴⁰Ca
21	⁴²Sc	⁴⁰Sc
22	⁴³Ti	⁴⁰Ti
23	⁴⁴V	⁴⁰V
24	⁴⁵Cr
25	⁴⁶Mn
26	⁴⁷Fe
27	⁴⁸Co
28	⁴⁹Ni