Question

What are the group 18 elements called?

Answer 1

Hint: In the modern periodic table there are a total of 18 groups and 6 periods. The 18 group is the last group in the periodic table and is placed at the extreme right. There are a total of 7 elements present in this group which is also numbered as ‘VIII A’.

Complete answer:
Group 18 of the periodic table has more than one name. It is generally called ‘Noble gases’ because they have completely filled outermost orbitals (octets).
But chemists also refer to it as ‘Inert gases’ as they do not react with any other element. They are inert towards chemical reactions. Initially, the group was also labelled as ‘rare elements’, due to their less availability in nature. But today they are quite abundant in nature so the word ‘rare element’ isn’t apt to use.
Although it is the 18^th group, it was termed as ‘Group 0’ in the past since no elements from this group could react and form new compounds.
The seven elements present in the group according to the increasing order of their Atomic number are:
Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Oganesson (Og). [Oganesson is the newly named element of the periodic table].

Element	Atomic number	Electronic configuration
He	2	$1{{s}^{2}}$
Ne	10	$[He]\text{ 2}{{\text{s}}^{2}}\text{ 2}{{\text{p}}^{6}}$
Ar	18	$[Ne]\text{ 3}{{\text{s}}^{2}}\text{ 3}{{\text{p}}^{6}}$
Kr	36	$[Ar]\text{ 3}{{\text{d}}^{10}}\text{ 4}{{\text{s}}^{2}}\text{ 4}{{\text{p}}^{6}}$
Xe	54	$[Kr]\text{ 4}{{\text{d}}^{10}}\text{ 5}{{\text{s}}^{2}}\text{ 5}{{\text{p}}^{6}}$
Rn	86	$[Xe]\text{ 4}{{\text{f}}^{14}}\text{ 5}{{\text{d}}^{10}}\text{ 6}{{\text{s}}^{2}}\text{ 6}{{\text{p}}^{6}}$
Og	118	\[\left[ Rn \right]\text{ }5{{f}^{1}}^{4}\text{ }6{{d}^{1}}^{0}\text{ }7{{s}^{2}}\text{ }7{{p}^{6}}\]

Excluding Helium all the other elements have the valence shell electronic configuration: $\text{n}{{\text{s}}^{2}}\text{ n}{{\text{p}}^{6}}$.
Properties of Noble gases:
These gases are colourless, tasteless, and odourless.
They have low melting and boiling points due to weak interatomic forces.
All the elements of this group are monatomic at standard conditions even the elements with high atomic numbers.
These gases are non-flammable.

Note:
 The uses of Noble gases are derived from their chemical properties. Their low melting and boiling points make it easy to study the matter and its properties at low temperatures. The noble gases have formed only a few hundred compounds to date. Also, these elements can form covalent as well as non-covalent bonds.