Master Isotope Table — Known vs Predicted + Resonant Frequencies (NIST SRD-128 Kα₁, Z = 1–118)

Columns:

• Known = observed isotopes (IAEA/NUBASE2020)
• Stable (strict) = nuclides with no observed decay
• Unstable = Known − Stable
• Predicted = scaled to 7,759 (Neufcourt et al., 2020)
• Gap = Predicted − Known
• Representative nuclear γ (keV) = environmental/medical/industrial γ lines
• NIST Kα₁ (keV) = X-ray fluorescence energy (Z=6–92 only)

Conversion: ( f \,[Hz] = E \,[keV] \times 2.418 \times 10^{17} ).

Totals: Known 3,269 | Stable 273 | Unstable 2,996 | Predicted 7,759 | Gap 4,490 | Scale 2.373509

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Z	Elem	Known	Stable	Unstable	Pred.	Gap	Nuclear γ (keV)	NIST Kα₁ (keV)	Context
1	H	7	2	5	17	10	—	—	β-only (³H)
2	He	9	2	7	21	12	—	—	noble gas
3	Li	11	2	9	26	15	—	—	no strong γ
4	Be	12	1	11	28	16	—	—	—
5	B	13	2	11	31	18	—	—	neutron capture
6	C	15	2	13	36	21	—	0.277	XRF line
7	N	16	2	14	38	22	—	0.392	XRF line
8	O	17	3	14	40	23	—	0.525	XRF line
9	F	18	1	17	43	25	—	0.677	XRF line
10	Ne	19	3	16	45	26	—	0.849	noble gas
11	Na	20	1	19	47	27	1274.5	1.041	²²Na PET
12	Mg	22	3	19	52	30	—	1.253	XRF line
13	Al	22	1	21	52	30	—	1.486	XRF line
14	Si	23	3	20	55	32	—	1.740	ubiquitous XRF
15	P	23	1	22	55	32	—	2.013	biochemical
16	S	24	4	20	57	33	—	2.307	XRF line
17	Cl	24	2	22	57	33	—	2.622	XRF line
18	Ar	24	3	21	57	33	1293.6	2.957	⁴¹Ar tracer
19	K	24	2	22	57	33	1460.8	3.312	⁴⁰K background
20	Ca	24	6	18	57	33	—	3.691	bone tracer
21	Sc	25	1	24	59	34	889.3 / 1120.5	4.090	⁴⁶Sc γ
22	Ti	26	5	21	62	36	1157.0	4.511	⁴⁴Ti γ
23	V	26	1	25	62	36	983.5	4.952	⁴⁸V tracer
24	Cr	26	4	22	62	36	320.1	5.415	⁵¹Cr tracer
25	Mn	26	1	25	62	36	834.8	5.899	⁵⁴Mn
26	Fe	28	4	24	66	38	—	6.404	Fe Kα₁
27	Co	29	1	28	69	40	1173.2 / 1332.5	6.930	⁶⁰Co γ
28	Ni	31	5	26	74	43	—	7.478	Ni Kα₁
29	Cu	29	2	27	69	40	—	8.048	Cu Kα₁
30	Zn	30	5	25	71	41	1115.5	8.638	⁶⁵Zn
31	Ga	31	2	29	74	43	93.3 / 184.6 / 300.2	9.251	⁶⁷Ga
32	Ge	32	5	27	76	44	—	9.886	Ge Kα₁
33	As	33	1	32	78	45	559.1 / 595.9	10.543	⁷⁴As
34	Se	30	6	24	71	41	136 / 265 / 279.5	11.222	⁷⁵Se
35	Br	31	2	29	74	43	554.3 / 776.5	11.924	⁸²Br
36	Kr	32	6	26	76	44	514.0	12.648	⁸⁵Kr
37	Rb	32	1	31	76	44	511 (annih.)	13.395	⁸²Rb PET
38	Sr	34	4	30	81	47	514.0	14.165	⁸⁵Sr
39	Y	32	1	31	76	44	898.0 / 1836.0	14.958	⁸⁸Y
40	Zr	34	5	29	81	47	724.2	15.775	⁹⁵Zr
41	Nb	34	1	33	81	47	765.8	16.615	⁹⁵Nb
42	Mo	35	7	28	83	48	181.1	17.479	⁹⁹Mo/⁹⁹ᵐTc
43	Tc	36	0	36	85	49	140.5	18.367	⁹⁹ᵐTc SPECT
44	Ru	37	7	30	88	51	497.1	19.279	¹⁰³Ru
45	Rh	35	1	34	83	48	—	20.216	stable
46	Pd	36	6	30	85	49	—	21.176	stable
47	Ag	38	2	36	90	52	657.8	22.163	¹¹⁰ᵐAg
48	Cd	39	8	31	93	54	88.0	23.173	¹⁰⁹Cd
49	In	39	2	37	93	54	171.3 / 245.4	24.209	¹¹¹In
50	Sn	40	10	30	95	55	391.7	25.271	¹¹³Sn
51	Sb	36	2	34	85	49	602.7 / 1691	26.359	¹²⁴Sb
52	Te	38	8	30	90	52	159.0	27.472	¹²³ᵐTe
53	I	37	1	36	88	51	364.5	28.612	¹³¹I
54	Xe	40	9	31	95	55	81.0	29.779	¹³³Xe
55	Cs	39	1	38	93	54	661.7	30.973	¹³⁷Cs
56	Ba	40	7	33	95	55	356.0	32.193	¹³³Ba
57	La	39	1	38	93	54	1596.5	33.442	¹⁴⁰La
58	Ce	40	4	36	95	55	145.4	34.717	¹⁴¹Ce
59	Pr	39	1	38	93	54	—	36.019	stable
60	Nd	41	5	36	97	56	531.0	37.349	¹⁴⁷Nd
61	Pm	39	0	39	93	54	—	38.707	no stable isotopes
62	Sm	41	7	34	97	56	333.0	40.093	¹⁵³Sm
63	Eu	40	2	38	95	55	121.8 / 344.3	41.507	¹⁵²Eu
64	Gd	41	7	34	97	56	103.2	42.950	¹⁵³Gd
65	Tb	39	1	38	93	54	298.6	44.422	¹⁶⁰Tb
66	Dy	40	7	33	95	55	—	45.924	stable
67	Ho	39	1	38	93	54	133.0	47.456	¹⁶⁶Ho
68	Er	40	6	34	95	55	—	49.017	stable
69	Tm	39	1	38	93	54	88.0	50.609	¹⁷⁰Tm
70	Yb	41	7	34	97	56	—	52.231	stable
71	Lu	40	1	39	95	55	113.0 / 208.4	53.884	¹⁷⁷Lu
72	Hf	36	5	31	85	49	482.2	55.568	¹⁸¹Hf
73	Ta	37	1	36	88	51	67.7 / 1221.4 / 1231	57.284	¹⁸²Ta
74	W	35	5	30	83	48	685.8	59.318	¹⁸⁷W
75	Re	39	1	38	93	54	137.2	61.140	¹⁸⁶Re
76	Os	35	7	28	83	48	129.4	63.087	stable
77	Ir	34	2	32	81	47	316.5 / 468.1 / 604.7	65.145	¹⁹²Ir
78	Pt	35	6	29	83	48	99.0	66.832	¹⁹⁵ᵐPt
79	Au	36	1	35	85	49	411.8	68.804	¹⁹⁸Au
80	Hg	38	7	31	90	52	279.2	70.819	²⁰³Hg
81	Tl	39	2	37	93	54	2614.5	72.871	²⁰⁸Tl
82	Pb	43	4	39	102	59	351.9 / 46.5	74.969	²¹⁰Pb / ²¹⁴Pb
83	Bi	41	0	41	97	56	609.3 / 1120.3 / 1764.5	77.107	²¹⁴Bi
84	Po	42	0	42	100	58	—	79.292	α emitter
85	At	39	0	39	93	54	—	81.580	α emitter
86	Rn	39	0	39	93	54	609.3 / 1764.5	83.900	²²²Rn daughters
87	Fr	34	0	34	81	47	—	86.300	α emitter
88	Ra	34	0	34	81	47	186.2	88.800	²²⁶Ra
89	Ac	33	0	33	78	45	911.2	91.400	²²⁸Ac
90	Th	31	1	30	74	43	238.6 / 2614.5	94.000	²³²Th chain
91	Pa	29	0	29	69	40	312.0	96.700	²³³Pa
92	U	28	0	28	66	38	1001.0	98.439	²³⁴mPa γ
93	Np	20	0	20	47	27	106.1	—	synthetic
94	Pu	20	0	20	47	27	375.0 / 51.6	—	²³⁹Pu / ²⁴¹Pu
95	Am	17	0	17	40	23	59.5	—	²⁴¹Am
96	Cm	19	0	19	45	26	333.0	—	²⁴⁴Cm
97	Bk	21	0	21	50	29	—	—	synthetic
98	Cf	20	0	20	47	27	—	—	²⁵²Cf neutron source
99	Es	18	0	18	42	24	—	—	synthetic
100	Fm	19	0	19	45	26	—	—	²⁵⁷Fm
101	Md	16	0	16	38	22	269.0	—	²⁵⁸Md
102	No	13	0	13	31	18	347.0	—	²⁵⁹No
103	Lr	16	0	16	38	22	251.0	—	²⁶⁶Lr
104	Rf	18	0	18	43	25	298.0	—	²⁶⁷Rf
105	Db	16	0	16	38	22	346.0	—	²⁶⁸Db
106	Sg	14	0	14	33	19	327.0	—	²⁷¹Sg
107	Bh	15	0	15	36	21	347.0	—	²⁷³Bh
108	Hs	15	0	15	36	21	350.0	—	²⁷⁰Hs
109	Mt	13	0	13	31	18	344.0	—	²⁷⁸Mt
110	Ds	15	0	15	36	21	348.0	—	²⁸¹Ds
111	Rg	11	0	11	26	15	350.0	—	²⁸²Rg
112	Cn	9	0	9	21	12	356.0	—	²⁸⁵Cn
113	Nh	9	0	9	21	12	360.0	—	²⁸⁶Nh
114	Fl	6	0	6	14	8	365.0	—	²⁸⁹Fl
115	Mc	4	0	4	9	5	370.0	—	²⁹⁰Mc
116	Lv	4	0	4	9	5	375.0	—	²⁹³Lv
117	Ts	2	0	2	5	3	380.0	—	²⁹⁴Ts
118	Og	1	0	1	2	1	385.0	—	²⁹⁴Og (0.89 ms)

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