why are the elements of s block more bigger than d block elements?
why are the elements of s block more bigger than d block elements?
The ionic sizes shows gradual decrease as we move right across a series. This is because as we number of electrons increase, the nuclear charge too increase. Due to poor shielding of nuclear charge by d-electrons, the net increase in nuclear charge outweighs the effect of added electron, thereby reducing the size.
Similar trend and reasons can be observed for case of atomic radii as well, though the decrease is much gradual. In case of going down the series, the atomic radii shows increase. There is a huge jump from 3d to 4d in terms of atomic size, but the 4d and 5d series have a small difference only. This is explained on the basis of Lanthanoid contraction. In case of 5d series, the inner 4f orbitals are filled before 5d orbitals. The poor shielding ability of 4f electrons renders the outer electrons greater nuclear pull, causing lanthanoid contraction. Due to this, the expected increase in atomic size is compensated by increased nuclear pull, keeping the size nearly same.
The ionic sizes shows gradual decrease as we move right across a series. This is because as we number of electrons increase, the nuclear charge too increase. Due to poor shielding of nuclear charge by d-electrons, the net increase in nuclear charge outweighs the effect of added electron, thereby reducing the size.
Similar trend and reasons can be observed for case of atomic radii as well, though the decrease is much gradual. In case of going down the series, the atomic radii shows increase. There is a huge jump from 3d to 4d in terms of atomic size, but the 4d and 5d series have a small difference only. This is explained on the basis of Lanthanoid contraction. In case of 5d series, the inner 4f orbitals are filled before 5d orbitals. The poor shielding ability of 4f electrons renders the outer electrons greater nuclear pull, causing lanthanoid contraction. Due to this, the expected increase in atomic size is compensated by increased nuclear pull, keeping the size nearly same.
