Alice in Hydrogen Land
By
Kelvin Kemm
|
July 10th, 2026
At a shopping mall or amusement park one can see vendors selling balloons filled with Helium. Kids love them and dance around trailing their balloons, which float above them. From time to time some kid accidentally lets go and you see the balloon soaring high into the sky, to the delight of many watching, but to the heartbreak of the kid. The balloon soars up into the sky because it is filled with Helium, and Helium is a gas much lighter than the Oxygen and Nitrogen which make up most of the atmosphere.
Atoms are made-up of a nucleus, and electrons which orbit around the nuclei, Each nucleus is composed of neutrons and protons. The mass of each atom is essentially the mass of the total number of neutrons and protons in a nucleus. The scientifically quoted masses are not whole numbers because the atoms of a single element have slight variations in the number of neutrons. These variations are called isotopes. So, the quoted mass of Oxygen, for example, is 15.999 which is not a round number. But for now, I will just use the closest round number, so Oxygen will be 16. These numbers are measured in Atomic Mass Units, so Oxygen is 16 amu. Nitrogen is 14, and Helium is 4. As you can see, the Helium is way lighter than Oxygen or Nitrogen, and that is why a Helium balloon shoots up into the sky so fast when the kid lets go. But there is an additional factor, and that is that in nature the atoms exist as molecules. Both the Oxygen and Nitrogen molecules consist of two atoms each, but the Helium molecule is only one atom. So, the molecular masses in the air are actually; Oxygen 32, Nitrogen 28, and Helium is still 4.
Golf balls in a fishing net
But now a universal disappointment for kids. The kid has fun with the balloon all day, and then usually ties it to a chair so that he can play with it again in the morning. But when he comes to look at it in the morning it is nearly flat and typically lying on the floor. This disappointing sight then generates much discussion as to what went wrong during the night. The answer is quite simple. The Helium atom is not only light in mass, but is also very small in comparison to the Oxygen and Nitrogen atoms. It is like comparing a soccer ball and a golf ball, if you are looking at Oxygen and Helium. In fact, two soccer balls glued together, because the Oxygen has to exist as a 2-atom molecule. Imagine filling a fishing net with pairs of soccer balls glued together. You can easily carry a whole load of double soccer balls in a fishing net with no problem. But you can’t fill the fishing net with a load of golf balls, because they will all fall through the net holes. In the case of a balloon the wall of the balloon is not solid, it is in effect a net. The spaces between the big molecules which make up the balloon are small enough that Oxygen and Nitrogen can’t get through, but Helium can. So what actually happens during the night, is that the Helium just leaks out through the wall of the balloon, much to the disappointment of the child.
These difference in sizes of the molecules also present problems in industry. Pipelines which have joints, valves, and all sorts of steps in a production process will readily contain Oxygen or Nitrogen, but can very easily leak Helium. So, making a Helium pipeline is far more difficult than making an Oxygen pipeline.
Hydrogen heartache
Excerpt:
https://wattsupwiththat.com/2026/07/10/alice-in-hydrogen-land/
