| Symbol |
Name |
Atomic
Number |
Atomic
Weight |
Group
Number |
| Pm |
Promethium |
61 |
145 |
|
Description
Standard State: Solid at 298 K
Color: metallic
In 1902, Branner predicted the existence of an element between neodymium and samarium,
and this was confirmed by Moseley in 1914. In 1941, workers at Ohio State University
irradiated neodymium and praseodymium with neutrons, deuterons, and alpha particles and
produce several new radioactivities, which most likely were element 61. Wu and Segre, and
Bethe, in 1942, confirmed the formation; however, chemical proof of the production of
element 61 was lacking because of the difficulty in separating the rare earth elements
from each other at that time. The element has applications as a beta source for thickness gages, and it can be
absorbed by a phosphor to produce light. Light produce in this manner can be used
for signs or signals that require dependable operation. Promethium shows promise as
a portable X-ray unit.
|