(chemistry) a periodic table

oganesson

period of time, cycle

last, end, conclusion / last, final

once

(chemistry) element, chemical element

surface; face (visible side of an object) / front (of a building), obverse side of a coin ("heads") / cover attached to a surface / outer clothing / facade; appearance; outside; exterior

table, chart, list / documents presented to a monarch from a vassal or other foreign dignitary

front of something

appearance / expression / surface / front / exterior / outward / outwardly / outward appearance / countenance