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Fl

Flerovium

properties predicted

Flerovium (Fl) is a post-transition metal with atomic number 114. It has no stable isotope and no characteristic isotopic composition on Earth, so it has no standard atomic weight. CIAAW lists flerovium-289 and flerovium-290 as its longest-lived isotopes, and the mass number used here is 289. Its electron configuration is predicted to be [Rn] 5f14 6d10 7s2 7p2, which gives it 4 valence electrons.

Flerovium key data

Symbol Fl
Atomic number 114
Mass number (one of its longest-lived isotopes) 289
Protons 114
Neutrons (flerovium-289) 175
Electrons (neutral atom) 114
Valence electrons 4
Category Post-transition metal
Period 7
Group 14
Block p-block
Noble gas notation [Rn] 5f14 6d10 7s2 7p2
Full electron configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p2
Electrons per shell 2, 8, 18, 32, 32, 18, 4

Mass number: IUPAC CIAAW radioactive elements, from NUBASE2020.

The values are facts and free to use; this page’s selection and presentation are © 2026 ScienceQuest.

Properties of flerovium

From PubChem, the US National Institutes of Health. Public domain. Most properties of this element are predicted, because only a few atoms have ever been made.

Predicted state at room temperature Solid
Predicted oxidation states +6, +4, +2, +1, 0
Discovered 1998

Flerovium electron configuration

The full electron configuration of flerovium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p2. With the noble-gas core collapsed it is [Rn] 5f14 6d10 7s2 7p2, and the outermost subshell is 7p2.

Bohr model of flerovium (Fl): a nucleus and seven shells holding 2, 8, 18, 32, 32, 18 and 4 electrons from the inside out.
Bohr model of flerovium (Fl). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.
Orbital box diagram of flerovium (Fl), [Rn] 5f14 6d10 7s2 7p2, with the radon core drawn as one bar: one box per orbital, filled by Hund’s rule, showing two unpaired electrons, in 7p.
Orbital diagram of flerovium (Fl). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one flerovium atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

  1. one atom = 289 / (6.02214076 × 10²³)
  2. = 4.7990 × 10⁻²² g

Atoms in one gram

  1. atoms per gram = 6.02214076 × 10²³ / 289
  2. = 2.0838 × 10²¹ atoms

Flerovium has no standard atomic weight, because it has neither a stable isotope nor a characteristic isotopic composition on Earth. The figure used above is the mass number of flerovium-289, so treat these as nominal.

Flerovium on the periodic table

Flerovium is in period 7, group 14, in the p-block.

The other elements of group 14 are carbon, silicon, germanium, tin and lead.

The rest of period 7

Work with flerovium