Question

Write the general electronic configuration of the noble gas group. Which element of this group is used in magnetic resonance imaging (MRI)?

Answer 1

Elements of the noble gas group have their valence shell orbital completely filled. The noble gas used in MRI is colourless as well as odourless having atomic number 2 with a mass number of 4. It is the second most common element in the Universe, after hydrogen.

Complete answer:
Group-18 elements or the noble gas group has a general electronic configuration of $n{{s}^{2}}n{{p}^{6}}$ except helium which has $1{{s}^{2}}$. Among the group-18 elements, helium is used in magnetic resonance imaging (MRI) due to its unique properties. Let us see what are they:
-Noble gas mainly consists of six elements: helium($^{4}H{{e}_{2}}$), neon($^{20}N{{e}_{10}}$), argon($^{40}A{{r}_{18}}$), krypton($^{84}K{{r}_{36}}$), xenon($^{131}X{{e}_{54}}$), radon($^{222}R{{n}_{86}}$). Among these, radon is the only element showing radioactive properties.
They have fully-filled valence orbital and, therefore, are inert and react with a few elements only under certain extreme conditions. Therefore, they are known as noble gas due to their low reactivity.
All the noble gases except radon occur in the atmosphere. Their atmospheric abundance in dry air is about $1$ by volume of which argon is the major constituent. Sometimes, helium and neon are found in minerals of radioactive eg: pitchblende, monazite, etc.
The last orbital of the noble elements are p orbital except helium(s-orbital). These p-orbitals of noble gas are fully filled i.e it contains six electrons in total.
One of the noble elements is helium which is used for varied purposes. One of them is its use in MRI. Helium has some special characteristics for which it becomes ideal to use in MRI.
Helium is a light, odourless, colourless, inert, monatomic gas. It can form diatomic molecules, but is weak enough and at temperatures close to absolute zero. Helium has the lowest melting point and its boiling point is close to absolute zero. These properties make helium perfect to use in magnetic resonance imaging(MRI).

Note:
Helium also has low density, high stability, and it’s extremely small size makes it suitable to use in MRI.