An element that needs to be excluded, on principle, from the Periodic Table, say some. Its specific hazards are described in the tome-like treatise "The Perils of Paulinium" , by Dudley Doright.
Alternates between a rigid state and a malleable state. Over time the malleable periods become more protracted, and the rigid state becomes harder to achieve.
Originally dismissed as mere hearsay, this element was re-discovered in the Australian jungle and is now used in the advertising business. Not as you might think a halogen, but a different klass altogether.
Tends to aggregate in stable blocks. Most commonly found in areas of high amenity value. The market in this element fluctuates wildly leading to it being a factor in speculative excesses.
A lumpy, hard substance which is occasionally used in competitive events. Participants attempt to gather as much of it as possible, the winner being the player with the most Nobblinese. Once common in holiday camps, it may still be found around seaside piers and anywhere frequented by the elderly.
An element formerly used in the manufacture of radios. If someone offers you an antique radio, check its authenticity by looking for the word "Hilversum" written on the tuning dial.
Mostly found in rock formations. Capable of absorbing its own atomic weight in carbon-attached hydroxyl group compounds, but tends to sweat and emit a noxious odour when subjected to energy.
Useful element in most experiments. When treated with care, will remind you of the date of the experiment, set up the lab beforehand and write up the notes afterwards. Can get overexcited. Occasionally becomes unstable. [Projoy] Top notch.
The fifth isotope of Symphonium, discovered in early 19th century Germany, but in a bizarre irony, it's first practical use was as part of the United Kingdom's war machine in world war two.