See also: List of individual Erbium isotopes (and general data sources).
General data
Name of the isotope:Erbium-168; Er-168Symbol:168Er or 16868ErMass number A:168 (= number of nucleons)Atomic number Z:68 (= number of protons)Neutrons N:100Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.4705882352941 (= neutron-proton ratio)Neutron excess (N-Z):32Isotopic mass:167.93238(2) u (atomic weight of Erbium-168)Nuclide mass:167.8950799 u (calculated nuclear mass without electrons)Mass excess:-62.98762 MeVMass defect:1.466213776 u (per nucleus)Nuclear binding energy:1365.76933506 MeV (per nucleus) 8.12957938 MeV (average binding energy per nucleon)Separation energy:SN = 7.77131(12) MeV (first neutron) SP = 8.000(5) MeV (first proton)Half-life:stableSpin and parity: (nuclear angular momentum)0+Charge radius:5.2644(35) femtometer fmYear of discovery:1934
Comparison of the natural Erbium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):
Atomic Mass ma
Quantity
Half-life
Spin
Erbium Isotopic mixture
167.259 u
100 %
Isotope 162Er
161.92879(2) u
0.139(5) %
stable
0+
Isotope 164Er
163.92921(2) u
1.601(3) %
stable
0+
Isotope 166Er
165.93030(2) u
33.503(36) %
stable
0+
Isotope 167Er
166.93205(2) u
22.869(9) %
stable
7/2+
Isotope 168Er
167.93238(2) u
26.978(18) %
stable
0+
Isotope 170Er
169.93547(2) u
14.910(36) %
stable
0+
Isotones and Isobars
The following table shows the atomic nuclei that are isotonic (same neutron number N = 100) and isobaric (same nucleon number A = 168) with Erbium-168. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.
