Untriseptium





Untriseptium is a chemical element which has not yet been observed to occur naturally or be synthesised. Its atomic number is 137 and symbol is Uts.

The name untriseptium is a temporary IUPAC systematic element name.

History
Because the significance of element 137 was first pointed out by the physicist Richard Feynman, element 137 is sometimes informally called "feynmanium" (symbol Fy).

Significance
In a non-relativistic approximation, the speed of an electron in a 1s electron orbital, v, can be obtained using the expression:


 * $$v = Z \alpha c \approx \frac{Z c}{137.036}$$

where Z is the atomic number, and α is the fine structure constant, a measure of the strength of electromagnetic interactions. Under this approximation, any element with an atomic number of greater than 137 would require 1s electrons to be traveling faster than c, the speed of light.

A complete analysis involving relativity reduces the speed of electrons, therefore allowing stable 1s orbits in the element 138 (Uto).