Question

Write the name and symbol of the element from the description. The noble gas with the smallest atomic radius.

Answer 1

Hint Noble gases are also known by the name inert gases these are gases which have fully filled outermost shell, i.e. valence electrons are zero in this case and these gases have zero valencies. Noble gases are very stable in nature.

Complete Step by step solution:
Noble gases are generally colourless, odourless, monoatomic gases which show very low chemical reactivity because of their stable nature. There are six naturally occurring noble gases named as helium, neon, argon, krypton, xenon and radioactive radon. These are generally present in group 18 of the periodic table.
We know that an atom consists of a nucleus in its centre and the atomic radius of a chemical element measures the size of its atoms which is usually determined by the distance from the centre of the nucleus to the outermost shell of electrons. Atomic radius is defined by three categories named as van der Waals radius, ionic radius and covalent radius.
As we move from Helium represented by the symbol He to radon represented by Rn then atomic radii increases due to increase in the number of shells so we can consider that first member of noble gases i.e. Helium shows the smallest atomic radii.

Note: Atomic radii decreases as we move from left to right across a period due to increase in effective nuclear charge and atomic radii increases as we move from top to bottom due to increase in a number of shells.