Having talked about Hydrogen last week, this week it is the turn of Helium. This well known gas is best known for its ability to make balloons float and for making your voice squeaky.
How does it make balloons float? Well, like hydrogen, Helium is one of the lightest molecules. It is lighter or less dense than air and so if you fill a balloon with Helium the balloon will rise up through the air and float. A balloon containing hydrogen would also float in air but Helium has a major advantage over hydrogen - Helium is much safer. Hydrogen with its single electron is very reactive and a tiny spark causes it to burn in air to produce water. As we saw last week, when controlled in a rocket's engine this is a very useful reaction. It is much more difficult to control in a balloon. In the past Hydrogen was used to lift balloons and air ships and was in use until the Hindenburg Disaster in 1937 when the hydrogen balloon carrying an airship burst into flames killing many of the passengers.
So why is Helium so much safer than hydrogen? Well the reason Helium is number 2 on the periodic table of elements is because it has 2 electrons. An atom with 2 electrons is content to stay like that and has no need to share, give away or look for extra electrons. A Helium atom reminds me of a family with twins. Just like twins, the 2 Helium electrons are happy with their own company. This means that Helium is not reactive or as scientists would say - inert.
Could Helium balloons be used to lift a person? There are various reports of people using Helium balloons to fly. A plane is reported to have contacted the control tower reporting a man on a deckchair floating in the flight path being lifted by Helium balloons. Apparently he kept attaching balloons to the chair and eventually it took off. He was unable to reach the balloons to burst them and was floating, unable to return to earth when the pilot saw him. He was rescued by a helicopter.
Others have not been so lucky and have drifted off never to be seen again.
I reckon it would take a lot of Helium balloons to lift a person - According to our experiments each balloon can lift approx 5g. At that rate you would need 200 balloons to lift 1kg! No matter how many balloons you would need do not try it. It is definitely one of those experiments which you MUST NOT try at home.
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