Why is dihelium less likely to exist than dihydrogen?
To understand why dihelium (He2) is less likely to exist than dihydrogen (H2), we need to consider the electronic structure and bonding behavior of these elements.
Dihydrogen (H2) is formed by sharing two electrons between two hydrogen atoms, creating a covalent bond. Hydrogen atoms have one electron each, so they can readily share their electrons to achieve a stable electron configuration, which is similar to that of helium (He).
On the other hand, dihelium (He2) would require two helium atoms to share their electrons in order to form a bond. However, helium atoms have a stable electron configuration with a full outer shell consisting of two electrons. Helium is referred to as a noble gas precisely because its electron configuration is stable and does not readily form bonds with other atoms. This stability makes it unlikely for helium atoms to share their electrons and form a dihelium molecule. The electron-electron repulsion between the two helium atoms would also be another contributing factor that hinders the formation of He2.
Therefore, due to the unique electronic structure of helium and its strong tendency to maintain its stability, dihelium is highly unlikely to exist under normal conditions.