How the character is built
气
The 气 radical marks this as a gas, and that is not a coincidence of this one character — it holds right across the table. Read the radical first and the element's state at room temperature is already settled.
From 奥加涅相 (Oganessian); the gas radical follows its group even though oganesson is actually predicted to be a solid.
This character is used for the element and little else — you are unlikely to meet it outside a chemistry classroom.
Where it sits among the 118
Nothing here has ever existed in bulk, so Oganesson has no measured melting point, density or natural abundance — the figures published for it are predictions, and they disagree with each other.
First isolated in 2002.
Others built the same way
Every one of these carries 气, and every one is a gas.