1.Element in Group 18 of Periodic Table are
2.These elements are known as noble gases or rare gases.
3.They are the least reactive elements because their atoms have 8 valence electrons in their atoms (octet structure) except helium (duplet structure).
4.They are very stable because their outermost shell in their atom are full.
Physical Properties of the Noble Gases
-Colourless gases at room temperature with low melting point and boiling points
-poor conductors of heat and electricity
-insoluble in water
-element with low density
Going down the group, the atomic size increases because the number of electron-filled shells in the atom increases.
The boiling point and melting point of noble gases increase because
-The atomic radius gets larger.
-The attractive force between the neighboring atoms increase.
-More heat energy is required to overcome these stronger forces of attraction between the atoms while melting or boiling.
Chemical Properties of the Noble Gases
1.The noble gases are chemically inert because their electron arrangement are very stable,with 8 electrons (octet structure) or 2 electrons (duplet structure).
2.Their atoms will not lose or gain electron and share electrons with other atoms.
Uses of Noble Gases
Helium
1.Helium us used to fill weather or advertisements balloons and air ships.Helium is safer than hydrogen because it is not flammable and is unlikely to cause explosion.
2.Helium also used to inflate air craft tyres sa it is lighter than air.
Neon
1.It is used mainly in advertising light as it gives an orange-red glow when current passes through it.
Argon
1.It is used to fill electric bulbs.
2.It is also used to provide a completely inert atmosphere for welding and making of steels.
Krypton
1.It is used in lasers to repair the retina of eye.
2.It is used in high speed photographic flash lamps.
Radon
1.It is radioactive and used to treat cancer.
Xenon
1.It is used in electronic flash guns.
