from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun physics
Formof the helium atomin which the spinsof the two electronsare parallel.
from Wiktionary, Creative Commons Attribution/Share-Alike License
In orthohelium, on the other hand, the tracks of the two electrons lie in the same plane, the one being circular, while the other is elliptical.
It occurs in two different modifications: one is called parhelium, and is the more stable, and the other is called orthohelium - these were supposed at first to be two different substances.