- What is meant by periodicity in properties of elements with reference to the periodic table?
- Why do all the elements of the same group have similar properties ?
- How will the tendency to gain electrons change as we go from left to right across a period? Why?
The properties of elements are not distinct and recur from time to time. In the periodic table, elements are arranged in such a manner, that the elements with similar properties are present in the same group.
The properties of elements depend upon their electronic configurations. The elements having similar electronic configurations have similar properties. As elements of the same group have similar electronic configurations, they have similar properties.
As we move from left to right across a period in the periodic table, the tendency to gain electron increases. On moving from left to right across a period in the periodic table, there is an increase in the nuclear charge of the elements. At the same time, the size of the elements decreases. As a result, the effective nuclear charge acting on the valence electrons increases. Hence, the tendency to gain electrons increases.