Iron-56

Properties and data of the isotope ⁵⁶Fe.

Contents

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

General data

Name of the isotope:Iron-56; Fe-56Symbol:⁵⁶Fe or 5626FeMass number A:56 (= number of nucleons)Atomic number Z:26 (= number of protons)Neutrons N:30Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.1538461538462 (= neutron-proton ratio)Neutron excess (N-Z):4Isotopic mass:55.934936(3) u (atomic weight of Iron-56)Nuclide mass:55.9206733 u (calculated nuclear mass without electrons)Mass excess:-60.60673 MeVMass defect:0.52846231199999 u (per nucleus)Nuclear binding energy:492.25947285 MeV (per nucleus)
8.79034773 MeV (average binding energy per nucleon)Separation energy:S_N = 11.19710(23) MeV (first neutron)
S_P = 10.18364(16) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)0+Charge radius:3.7377(16) femtometer fmMirror nucleus:Zinc-56Year of discovery:1923

Parent Nuclides

Direct parent isotopes are: ⁵⁶Co, ⁵⁶Mn.

Occurrence

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Iron Isotopic mixture	55.845 u	100 %
Isotope ⁵⁴Fe	53.939609(3) u	5.845(105) %	stable	0+
Isotope ⁵⁶Fe	55.934936(3) u	91.754(106) %	stable	0+
Isotope ⁵⁸Fe	57.933274(3) u	0.282(12) %	stable	0+
Isotope ⁵⁷Fe	56.93539195(29) u	2.119(29) %	stable	1/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 30) and isobaric (same nucleon number A = 56) with Iron-56. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 30	Isobar A = 56
13	⁴³Al
14	⁴⁴Si
15	⁴⁵P
16	⁴⁶S
17	⁴⁷Cl
18	⁴⁸Ar
19	⁴⁹K	⁵⁶K
20	⁵⁰Ca	⁵⁶Ca
21	⁵¹Sc	⁵⁶Sc
22	⁵²Ti	⁵⁶Ti
23	⁵³V	⁵⁶V
24	⁵⁴Cr	⁵⁶Cr
25	⁵⁵Mn	⁵⁶Mn
26	⁵⁶Fe	⁵⁶Fe
27	⁵⁷Co	⁵⁶Co
28	⁵⁸Ni	⁵⁶Ni
29	⁵⁹Cu	⁵⁶Cu
30	⁶⁰Zn	⁵⁶Zn
31	⁶¹Ga
32	⁶²Ge
33	⁶³As
34	⁶⁴Se