Question

The atom of element become larger and larger when we move toward left and below. how does it affects the chemical reactivity of element

Answer 1

When we move towards left along a period or down a group, the size of atom gets larger and larger.... In the case of period, nuclear charge is greater in the elements on left side(Eg. Na) than the elements on right side(Eg. Cl) .... In case of down a group, the increase in the number of shells cause the increase in atomic size....
When an element has a bigger atomic size, it become more metallic in nature i.e, it will give electrons more readily than others. In the periodic table Francium is the most metallic element but as it is radioactive, Cesium is considered the most reactive/ metallic.
Hence, when we increase the size of an atom, it becomes more metallic.
Note: If we reduce the size of an atom, the more non-metallic it becomes.