How does atomic radius change from left to right across a period in the periodic table?

decrease

Explanation:

Atomic radii is the measure of the size of its atoms, usually the mean distance from the centre of the nucleus to the boundary of the surrounding shells of electrons.

The elements in the periodic table are arranged in order of increasing atomic numbers. The horizontal rows are called as periods and vertical columns are called as groups.

The size of an atom decreases as we move across the period because the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.

As, the valence electrons come near to the nucleus due to the increased attraction between the nucleus and the shared pair of electrons.

Thus atomic radius decrease from left to right across a period in the periodic table.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.