Question

Write Scientific reason. A.atomic radius goes on decreasing while going from left to right in a period

Answer 1

Due to effective nuclear charge ,as it increases when we move from left to right due to addition of more electrons in the outer valence shell. As a consequence the atomic radii decreases.

Answer 2

On going from left to right across the periodic table, the number of electrons in the atom of the elements goes on increasing. Moreover, the number of shells remain the same. This leads to more attraction between the protons in the nucleus and electrons in the shells. Hence the electrons move closer to the nucleus and the size of the atom decreases. However it must be noted that the size of the noble gases do not fall in this sequence. Hence the size of the atoms of noble gases are quite big in relation to the other atoms. This occurs because the electrons in the shells of nobles gases are in octet or duplet configuration. Hence the forces of repulsion are high and the size increases.