Question

shouldnt the size of the atom increases as we move across the periodic table?(no of protons n neutrons increase as we move across periodic table)

Answer 1

As we go across the period, the number of protons and neutrons increase gradually but at the same time the no. of electrons also increase causing increase in the effective charge.
Also, the new electrons are added in the same orbital and not new orbitals thus there is no chance to increase the atomic size.
Due to only increase in effective charge, the atom actually contracts rather than expand. and atomic radii decreases.