- The “Noble Gases” are the last group in the Periodic Table, they also known as “inert gas”, due to their non-reactive behavior.
- This group consist of six elements, namely Helium, Neon, Argon, Kripton, Xenon and Radon.
- They are non-metallic, colourless gases at room temperature and pressure with very low melting points and boiling points.
- They form 1% of air, and most of this is argon.
- The size of atom increases down the group, due to the increase number of electron shell.
|Name||Proton number||Electron arrangement||Melting point||Boiling point|
Solubility and Conductivity
- All noble gas are insoluble in water.
- They are not conductor of heat and electricity.
Melting Point and Boiling Point
- As show in the table above, the melting and boiling point of noble gases are very low.
- This is because all noble gases exist as monoatoms. The force in between all these atoms is the weak van de Waals’ Force.
- Therefore very little energy is needed to overcome this force during melting and boiling.
- The density of noble gases are very low.
- Nevertheless, the density increases steadily down the group.
- Density of a substance is given by the equation “Density=Mass/Volume”.
- Down the group, both the mass and the volume increase, but increase of mass is faster than the volume, hence the density increases down the group.
- All the noble gases are non-reactive elements.
- This is because their valence shell is full of electrons.
- In the chemical world, an atom is in the chemically most stable state if their valence shell is full with eight electrons (or 2 electrons for the first shell.).
- Therefore all noble gases do not react with other elements, due to their stable electronic structure.
- They exist as single atoms, that is they are monatomic.