# Could diatomic helium exist? [closed]

I know that $\ce{He2}$ (homonuclear diatomic helium) does not exist because its bond order is zero. Since the bond order of $\ce{He2+} = 1/2$, that means that the positive $\ce{He2+}$ ion exists, but how does the positive ion exist if the neutral molecule doesn't?

## closed as unclear what you're asking by Klaus-Dieter Warzecha, Todd Minehardt, Jan, ringo, WildcatNov 29 '16 at 10:13

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• It does not last long when formed. – Lighthart Nov 28 '16 at 18:48
• – orthocresol Nov 28 '16 at 18:52
• – Mithoron Nov 28 '16 at 20:38

In the scheme you can clearly see how we arrive at the bond order of zero for $\ce{He2}$. Both, the bonding $\sigma$ and the anti-bonding combination $\sigma^{*}$ are doubly occupied. Dihelium is only held together by weak van der Waals forces.
In the case of the dihelium cation $\ce{He2+}$, one electron is removed from the anti-bonding orbital. There are now more electrons in bonding than anti-bonding orbitals. This effectively results in a net energy loss or bond energy gain, and the overall bond order increases to 0.5. In a more phenomenological context, three negative charges are now in a field of four positive charges, this gives rise to Coulomb attraction.