Francium (element)
鈁 centers on the chemical element francium, a rare and highly radioactive metal. Its meaning is narrowly scientific with no common abstract extensions.
鈁 is a modern character created for the element francium. It combines the metal radical 金 with the phonetic component 方 (ホウ), following the standard pattern for chemical element names.
The metal radical 金 tells you it is a metallic element. The right side 方 (ホウ) hints at the sound, so 鈁 is the metal that sounds like ホウ: francium.
For ホウ, imagine a scientist holding a glowing vial of francium and saying 'Ho!', amazed by its radioactivity: Ho! -> ホウ.