Mendelevium (Md, Z = 101): atomic energy levels
No energy level diagram can be drawn for neutral mendelevium: no excited level of the atom has been measured, so there is no observed transition to show. This page lists what is known instead, and marks every calculated number as theory.
What has been measured
Only the first ionisation potential, by surface ionisation of 251Md atoms one at a time on a hot tantalum surface followed by mass separation and alpha counting (6.59(13) eV). No atomic level or optical transition has been measured.
| Quantity | Value | Source |
|---|---|---|
| Ground configuration | [Rn] 5f13 7s2 NIST | NIST Atomic Spectra Database, Ground States and Ionization Energies table (retrieved 2026-10-02), row Md I |
| Ground term | 2F°7/2 NIST | NIST Atomic Spectra Database, Ground States and Ionization Energies table (retrieved 2026-10-02), row Md I (also data/nist/Md_I_levels.tsv) |
| First ionisation energy | 6.59 ± 0.13 eV measured | T.K. Sato et al., J. Am. Chem. Soc. 140, 14609 (2018), p. 14610 Table 1 and p. 14611 Table 2 (surface ionisation of 251Md on a tantalum surface at 2900 K, mass separation, alpha counting) |
| Longest-lived isotope | 258Md, half-life 51.59 ± 0.29 d | NUBASE2020: F.G. Kondev, M. Wang, W.J. Huang, S. Naimi, G. Audi, Chin. Phys. C 45, 030001 (2021), machine-readable table nubase_4.mas20.txt, line for 258Md |
Calculated transitions from the ground state
Theory only: none of these lines has been observed. Wavelengths are converted from the calculated level energies.
Sources
- T.K. Sato et al., J. Am. Chem. Soc. 140, 14609 (2018)
- J. Li, V. Dzuba, J. Quant. Spectrosc. Radiat. Transf. 247, 106943 (2020), arXiv:2002.08033v1, p. 2: 'To the best of our knowledge, there are no similar measurements or calculations for Md'
- M. Block, M. Laatiaoui, S. Raeder, Prog. Part. Nucl. Phys. 116, 103834 (2021), arXiv:2010.11941, Fig. 2 (p. 8: Md appears only with theoretical predictions) and p. 41