| Z | Elem | Known | Stable | Unstable | Pred. | Gap | Nuclear γ (keV) | f(γ) (Hz) | Kα₁ (keV) | f(Kα₁) (Hz) | Context |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 61 | Pm | 39 | 0 | 39 | 93 | 54 | — | — | 38.707 | 9.36×10^18 | No stable isotopes; XRF Kα₁ |
| 62 | Sm | 41 | 7 | 34 | 97 | 56 | 333.0 | 8.05×10^19 | 40.093 | 9.69×10^18 | ¹⁵³Sm therapy + XRF |
| 63 | Eu | 40 | 2 | 38 | 95 | 55 | 121.8 / 344.3 | 2.95×10^19 / 8.33×10^19 | 41.507 | 1.00×10^19 | ¹⁵²Eu calibration + XRF |
| 64 | Gd | 41 | 7 | 34 | 97 | 56 | 103.2 | 2.49×10^19 | 42.950 | 1.04×10^19 | ¹⁵³Gd imaging agent + XRF |
| 65 | Tb | 39 | 1 | 38 | 93 | 54 | 298.6 | 7.22×10^19 | 44.422 | 1.07×10^19 | ¹⁶⁰Tb therapy + XRF |
| 66 | Dy | 40 | 7 | 33 | 95 | 55 | — | — | 45.924 | 1.11×10^19 | Stable; XRF Kα₁ |
| 67 | Ho | 39 | 1 | 38 | 93 | 54 | 133.0 | 3.21×10^19 | 47.456 | 1.15×10^19 | ¹⁶⁶Ho therapy + XRF |
| 68 | Er | 40 | 6 | 34 | 95 | 55 | — | — | 49.017 | 1.18×10^19 | Stable; XRF Kα₁ |
| 69 | Tm | 39 | 1 | 38 | 93 | 54 | 88.0 | 2.13×10^19 | 50.609 | 1.22×10^19 | ¹⁷⁰Tm calibration + XRF |
| 70 | Yb | 41 | 7 | 34 | 97 | 56 | — | — | 52.231 | 1.26×10^19 | Stable; XRF Kα₁ |
| 71 | Lu | 40 | 1 | 39 | 95 | 55 | 113.0 / 208.4 | 2.74×10^19 / 5.03×10^19 | 53.884 | 1.30×10^19 | ¹⁷⁷Lu therapy + XRF |
| 72 | Hf | 36 | 5 | 31 | 85 | 49 | 482.2 | 1.17×10^20 | 55.568 | 1.34×10^19 | ¹⁸¹Hf tracer + XRF |
| 73 | Ta | 37 | 1 | 36 | 88 | 51 | 67.7 / 1221.4 / 1231 | 1.64×10^19 / 2.95×10^20 / 2.98×10^20 | 57.284 | 1.39×10^19 | ¹⁸²Ta γ emitter + XRF |
| 74 | W | 35 | 5 | 30 | 83 | 48 | 685.8 | 1.66×10^20 | 59.318 | 1.44×10^19 | ¹⁸⁷W tracer + XRF |
| 75 | Re | 39 | 1 | 38 | 93 | 54 | 137.2 | 3.31×10^19 | 61.140 | 1.48×10^19 | ¹⁸⁶Re therapy + XRF |
| 76 | Os | 35 | 7 | 28 | 83 | 48 | 129.4 | 3.13×10^19 | 63.087 | 1.52×10^19 | Stable + XRF |
| 77 | Ir | 34 | 2 | 32 | 81 | 47 | 316.5 / 468.1 / 604.7 | 7.65×10^19 / 1.13×10^20 / 1.46×10^20 | 65.145 | 1.58×10^19 | ¹⁹²Ir industrial γ + XRF |
| 78 | Pt | 35 | 6 | 29 | 83 | 48 | 99.0 | 2.39×10^19 | 66.832 | 1.61×10^19 | ¹⁹⁵ᵐPt (lab) + XRF |
| 79 | Au | 36 | 1 | 35 | 85 | 49 | 411.8 | 9.94×10^19 | 68.804 | 1.66×10^19 | ¹⁹⁸Au tracer + XRF |
| 80 | Hg | 38 | 7 | 31 | 90 | 52 | 279.2 | 6.75×10^19 | 70.819 | 1.71×10^19 | ²⁰³Hg environmental + XRF |
Key terms in plain language
Open a term for a concise explanation of language used on this page.
Broadband
A general term for always-on, high-speed Internet access. Broadband can be delivered over fiber, cable, DSL, fixed wireless, cellular, or satellite networks.
Cloud Computing
Computing resources—such as applications, servers, storage, or databases—delivered from remote infrastructure and scaled as requirements change.
Cybersecurity
The practices and controls used to protect identities, devices, networks, applications, and data from unauthorized access, disruption, or manipulation.
Identity and Access Management (IAM)
The systems and policies that determine who a user is, what resources they may access, and how that access is authenticated and reviewed.
API
An application programming interface is a defined way for software systems to exchange data or request functions from one another.
Artificial Intelligence (AI)
Software designed to perform tasks involving prediction, classification, generation, reasoning, or decision support. Business use still requires clear data, governance, security, and human accountability.