Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic charcter of elements very on moving down a vertical column ? How does the size of atomic radius vary on moving left to right in a horizontal row ? Give reason in pupport of your answer in the above two cases.

Explanation

Vertical Columns - Groups
Horizontal Rows - Period
Metallic character increases
Reason : Ability to lose electrons increases on moving down the group due to increase in distance between the nucleus and the valence electrons / decrease in the attraction between the nucleus and the valence electrons.
Atomic radius decreases
Reason : The nuclear charge increases on moving from left to right across a period resulting in increase in the attraction between the nucleus and the valence electrons.