Explain the variation of atomic radius along a period and down a group
Answers
Along a period moving left to right generally atomic radii decreases due to increase in proton but no. of shells remains constant hence net effective force by nucleus increases. In moving down the group no. of shells get added and hence effective force on outer shell decreases due to which size increase. There may be some exceptions due to shielding effect and screening effect.
Answer:
Atomic radius declines as we move from left to right in a period. It happens because in a period, the external electrons are available in a similar valence shell so, the atomic number increments from left to right in a period, which results in increase in the effective nuclear charge. Therefore, the attraction of electrons towards the nucleus is increased.
Also, atomic radius declines as we move from top to bottom in the group. It happens because as we move down in a group then there is increase in principal quantum number(n) which brings about increase in the distance between nucleus and the valence electrons.