From Hydrogen to Tellurium - HELIUM

Helium


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.

Chemistry - from Hydrogen to Tellurium

2011 is a special year for chemistry - it is the International Year of Chemistry. To celebrate this  Anyone 4 Science plans to write a blog introducing Chemistry to you. 


The plan to start at the very beginning - which according to the Sound of Music is a very good place to start. When you read you begin with A B C, when you sing you begin with Doh, Ray, Me but it is H, He, Li for Chemistry.......


Each week I am going to take a different element and write a few interesting facts. Hopefully by the end of the year you will know a little about all the elements from Hydrogen to Tellurium......... who knows I might even keep on going into 2012.



Hydrogen
So H,  why am I going to start there. Well H is the atomic symbol for Hydrogen, the smallest of all the atoms in the universe. All atoms are tiny, but hydrogen is the smallest of all. Even though they are tiny (more than a million can fit on the full stop at the end of this sentence), atoms are made up of different parts. Like all other atoms, Hydrogen is made up of a central nucleus containing protons and neutrons and Hydrogen has one of each. Spinning around or orbiting the nucleus are electrons and Hydrogen has just one of these. 


So what does an atom looks like. I like to think of them like fried eggs, where the yolk in the middle is like the nucleus and I imagine the electron whizzing around at the outside of the white part.

The dotted line shows the path the electron takes as it circles the nucleus.

Hydrogen atoms aren't very happy like this, maybe their electron gets lonely - who knows, anyway, rather than remain like this hydrogen prefers either to give away its electron so it has none or share an electron with another atom so it thinks it has 2. 

In nature, Hydrogen atoms always go around in pairs. Scientists write it as H2. I like to think of it as 2 fried eggs stuck together or maybe an egg with 2 yolks... The electrons orbit the 2 nucleii and both are tricked into believing that they both have 2 electrons. This H2 is known by scientists as the Hydrogen molecule.

Other interesting things about Hydrogen are

It is a gas

It is reactive.

It reacts with oxygen to create water and lots of energy. This is currently how rockets are fuelled. Many scientists hope that in the future we will be able to use Hydrogen instead of petrol and diesel for cars and heating. After it burns all that is left behind is water so there would be no polluting chemicals to be disposed of.

For more information about hydrogen check out http://www.chemicool.com/elements/hydrogen.html