TWIL #011 - There Might Be a Last Possible Element
The periodic table probably ends around element 173 - not because we'll run out of protons, but because electrons would have to exceed the speed of light.
- #physics
- #chemistry
- #periodic-table
We currently know of elements up to atomic number 118 (Oganesson). Heavier elements have been created briefly in labs but decay in milliseconds. The question is: how far can we theoretically go?
The answer, according to relativistic physics, appears to be around element 173.
Here's why. Electrons in an atom orbit the nucleus, and electrons in inner shells move faster as the nucleus gets heavier (more protons pulling harder). By element 137 - sometimes called the "Feynmanium" limit - the innermost electron's speed approaches the speed of light. Past that point, relativistic effects become severe.
For elements beyond about 173, the calculations suggest that the innermost electrons would need to travel faster than light to maintain stable orbits. Since that's physically impossible, the atom simply cannot hold together in a conventional sense. The electron would collapse into the nucleus.
There's some nuance - quantum mechanical corrections push the actual limit a bit further than the simple calculation suggests, and the exact number is still debated. But the principle is clear: the periodic table has a hard physical ceiling, not just a practical experimental one.
It's a strange thought. We think of the elements as a complete catalogue of matter, but it turns out even the catalogue has a last page - written in the laws of relativity.