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Heavy elements
Heavy elements
Elements heavier than helium on the periodic table. Elements as heavy as iron were formed by the fusion of lighter elements.
Helium (He)
Element 2 on the periodic table. An inert gas of group 8 (the noble gases).
It is colourless and odourless, and the second most common and second lightest element in the universe.
Helium was discovered by the French astronomer Pierre Janssen in 1868.
Helium is too light to be common in our atmosphere, although it is found combined with natural gas. Helium is obtained by liquefying natural gas. It is the last component to liquefy.
Helium is used in balloons and as an inert gas when there would otherwise be a risk of explosion.
 Helium – Helium is used in balloons because it is lighter than air.
Holmium (Ho)
Element 67 on the periodic table. A rare-earth metal and one of the lanthanides.
It is highly magnetic, but it has little practical use.
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 Hydrogen – The immense heat of the Sun is produced by burning hydrogen.
 Hydrogen – Hydrogen is the simplest of all elements. It has just one proton in its nucleus and one electron.
 Hydrogen – Hydrogen can be produced in a laboratory by reacting a dilute acid with a metal. The demonstration (right) uses dilute hydrochloric acid and zinc. Hydrogen is produced by the reaction in the flask.
The gas is then led through tubing into a water bath containing a gas jar supported on a beehive shelf. This is the standard way of collecting gases that are not soluble in water.