which chemical element has the lowest boiling point?

Is it Helium(He) or is it Hydrogen(H)?

Hydrogen is lighter than Helium.

  • $\begingroup$ Regardless of it is an element or a molecule,, helium has the lowest boiling point $(\pu{-269 ^\circ C})$. In comparison, hydrogen, which exists as a diatomic molecule, has the boiling point of $\pu{-253 ^\circ C}$. $\endgroup$ – Mathew Mahindaratne Jun 7 at 17:31

At its present form, this question is quite bad. I think you should've had a look at Wiki before asking this question. The boiling point of Hydrogen is around 20 K, while for Helium, it's around 4 K. I don't memorize these. But, I had a dirty look at Wiki. If you want a reason for why it has...

Helium has a stablest $1s$ orbital, which has somewhat lower energy. And, this makes it chemically inert towards other elements and to other Helium atoms, which is also the reason for its lowest boiling point.

  • 2
    $\begingroup$ The low boiling point of Helium is due to its very weak interatomic forces. I don't think the reactivity of helium with other helium atoms has much of a role here. Apparently quantum effects also play an important role in the case of Helium due to its small size. $\endgroup$ – kaliaden Apr 1 '13 at 15:24
  • $\begingroup$ @kaliaden: I don't know much. That was just a guess though ;-) $\endgroup$ – Waffle's Crazy Peanut Apr 1 '13 at 17:22

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