Tellurium-128

Properties and data of the isotope ¹²⁸Te.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Tellurium-128; Te-128Symbol:¹²⁸Te or 12852TeMass number A:128 (= number of nucleons)Atomic number Z:52 (= number of protons)Neutrons N:76Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.4615384615385 (= neutron-proton ratio)Neutron excess (N-Z):24Isotopic mass:127.904461(6) u (atomic weight of Tellurium-128)Nuclide mass:127.8759366 u (calculated nuclear mass without electrons)Mass excess:-88.99401 MeVMass defect:1.16097428 u (per nucleus)Nuclear binding energy:1081.44057597 MeV (per nucleus)
8.4487545 MeV (average binding energy per nucleon)Separation energy:S_N = 8.7833(17) MeV (first neutron)
S_P = 9.583(5) MeV (first proton)Half-life:7.7(4) × 10²⁴ aDecay constant λ:2.854487390868 × 10^-33 s^-1Specific activity α:1.353553161474 × 10^-11 Bq g^-1
3.658251787768 × 10^-22 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:4.7346(28) femtometer fmYear of discovery:1924

Radioactive Decay

Half-life T_½ = 7.7(4) × 10²⁴ a respectively 2.4282720 × 10³² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
2 β^-	¹²⁸Xe	100 %

Parent Nuclides

Direct parent isotopes are: ¹²⁸Sb, ¹²⁸I.

Occurrence

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

	Atomic Mass m_a	Quantity	Half-life	Spin
Tellurium Isotopic mixture	127.60 u	100 %
Isotope ¹²⁰Te	119.90406(2) u	0.09(1) %	stable	0+
Isotope ¹²²Te	121.90304(1) u	2.55(12) %	stable	0+
Isotope ¹²³Te	122.90427(1) u	0.89(3) %	9.2 × 10¹⁶ a	1/2+
Isotope ¹²⁴Te	123.90282(1) u	4.74(14) %	stable	0+
Isotope ¹²⁵Te	124.9044312(15) u	7.07(15) %	stable	1/2+
Isotope ¹²⁶Te	125.90331(1) u	18.84(25) %	stable	0+
Isotope ¹²⁸Te	127.904461(6) u	31.74(8) %	7.7(4) × 10²⁴ a	0+
Isotope ¹³⁰Te	129.90622275(8) u	34.08(62) %	0.79 × 10²¹ a	0+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 76) and isobaric (same nucleon number A = 128) with Tellurium-128. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 76	Isobar A = 128
42	¹¹⁸Mo
43	¹¹⁹Tc
44	¹²⁰Ru
45	¹²¹Rh
46	¹²²Pd	¹²⁸Pd
47	¹²³Ag	¹²⁸Ag
48	¹²⁴Cd	¹²⁸Cd
49	¹²⁵In	¹²⁸In
50	¹²⁶Sn	¹²⁸Sn
51	¹²⁷Sb	¹²⁸Sb
52	¹²⁸Te	¹²⁸Te
53	¹²⁹I	¹²⁸I
54	¹³⁰Xe	¹²⁸Xe
55	¹³¹Cs	¹²⁸Cs
56	¹³²Ba	¹²⁸Ba
57	¹³³La	¹²⁸La
58	¹³⁴Ce	¹²⁸Ce
59	¹³⁵Pr	¹²⁸Pr
60	¹³⁶Nd	¹²⁸Nd
61	¹³⁷Pm	¹²⁸Pm
62	¹³⁸Sm	¹²⁸Sm
63	¹³⁹Eu
64	¹⁴⁰Gd
65	¹⁴¹Tb
66	¹⁴²Dy
67	¹⁴³Ho
68	¹⁴⁴Er
69	¹⁴⁵Tm