Chemical properties of the noble gases
Compared to other A substance made of one type of atom only., the The elements in group 0 of the periodic table, named for their lack of chemical reactivity. are Unreactive. - they are extremely A substance is unreactive or inert if it does not easily take part in chemical reactions..
Explaining the inertness of noble gases
When elements react, their The smallest part of an element that can exist. complete their outer shells by losing, gaining, or sharing Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.. The atoms of noble gases already have complete outer shells, so they have no tendency to lose, gain, or share electrons. This is why the noble gases are inert and do not take part in chemical reactions.
The table summarises the The order electrons are arranged in different shells. of elements in groups 1, 7 and 0. You should see that:
- atoms of group 1 and 7 elements have incomplete outer shells (so they are The tendency of a substance to undergo a chemical reaction.)
- atoms of group 0 elements have complete outer shells (so they are unreactive)
Properties and uses of noble gases
The main The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point. of the noble gases include:
- they have low A measure of compactness and the ratio of mass to volume. It is usually measured in kilograms per metre cubed (kg/m3) or grams per centimetre cubed (g/cm3).
- they are inert, so they are not Able to ignite and burn.
Many uses of the noble gases are linked to one or more of these properties.
Helium
Helium is used as a lifting gas in party balloons and airships. Helium is:
- less dense than air, so balloons and airships rise
- non-flammable so the helium cannot set on fire
Argon
Argon is used as a 'shield gas' when Joining metals by melting and fusing the adjoining edges or surfaces. pieces of metal together. Argon is:
- denser than air, so it stops air getting to the metal
- inert, so the hot metal cannot The gain of oxygen, or loss of electrons, by a substance during a chemical reaction. and spoil the weld
Question
A common type of light bulb containing a thin coil of wire called the filament. contain thin metal wires. These become very hot and glow brightly when an The movement of electrically charged particles, for example, electrons moving through a wire or ions moving through a solution. is passed through them. Explain why argon, krypton or xenon are used in these lamps.
The hot metal wires will burn away if any oxygen from air is present in the lamp. Argon, krypton and xenon are very unreactive. They replace the air inside the lamp, preventing the metal wire from burning away.