Oganesson (Og) — element 118noble gas · group 18, period 7
Oganesson is a chemical element with the symbol Og and atomic number 118. It is a noble gas in group 18, period 7 of the periodic table (the p-block), with a standard atomic mass of [294] u. At room temperature (25 °C) oganesson is predicted to be a solid.
# Oganesson properties
| Symbol | Og |
|---|---|
| Atomic number | 118 |
| Atomic mass | [294] u |
| Category | noble gas |
| Group | 18 |
| Period | 7 |
| Block | p-block |
| Electron configuration | [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶ |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p⁶ |
| Electrons per shell | 2, 8, 18, 32, 32, 18, 8 |
| Protons / electrons | 118 / 118 |
| State at 25 °C | predicted solid |
| Melting point | 325 K (51.9 °C, 125.3 °F) (predicted) |
| Boiling point | 450 K (176.9 °C, 350.3 °F) (predicted) |
| Density | 5 g/cm³ (predicted) |
| Electronegativity (Pauling) | — |
| First ionization energy | — |
| Atomic radius | — |
| Discovered | 2002 |
Values for superheavy elements are theoretical predictions; none have been measured in bulk.
# Electron configuration of oganesson
The electron configuration of oganesson is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶, written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p⁶. Its 118 electrons fill 7 shells as 2, 8, 18, 32, 32, 18, 8, so the outermost shell holds 8 electrons. As a group 18 element, oganesson has 8 valence electrons. Because only a few atoms have ever been made, this configuration is a theoretical prediction.