Atomic Mass of Oganesson (Og)
Oganesson has no stable isotope, so no standard atomic weight exists; its most stable isotope has mass number ≈ 294, and the bracketed value [294] marks that estimate.
This is the fast lane: one page, one fact, zero digressions. Read the quick answer, check the table, and if your exam needs the full derivation, the sections below walk through it step by step — in Bangla and English, like every page here. Need the whole picture instead — history, characteristics, uses, exam questions? The full Oganesson page is one click away.
Oganesson by the numbers
One Oganesson atom carries 118 protons in its nucleus; add the neutrons of its commonest isotope (about 176) and you get its mass number, roughly 294.
| Quantity | Value |
|---|---|
| Atomic number (Z) | 118 |
| Relative atomic mass | [294] (no stable isotope) |
| Protons | 118 |
| Neutrons (commonest isotope) | 176 |
| Electrons | 118 |
Atomic mass vs mass number
Mass number (A) counts particles — protons + neutrons in one specific atom, always a whole number. Relative atomic mass is the experimentally measured average over all natural isotopes, so it comes out fractional ([294] is shown in brackets because it is only an estimate). Exams love this one-mark distinction.
Why is the mass in brackets?
Every isotope of Oganesson is radioactive and vanishes too quickly to build up a natural mixture — so the IUPAC convention prints the mass number of the longest-lived isotope in square brackets instead of a standard atomic weight.
Students also ask
Is the atomic mass of Oganesson a whole number?
No — Oganesson has no stable isotopes, so chemists use the bracketed estimate [294] rather than a measured average.
How many neutrons does Oganesson have?
Neutrons = mass number − atomic number. For Oganesson's commonest isotope that is about 294 − 118 = 176, though the exact count differs between isotopes.