What is periodicity in properties of elements with reference to the modern periodic table?
Why do all the elements of the same group have similar properties ? How does the tendency of elements to gain electrons change as we move from left to right in a period ? State the reason of this change.
(i) Repetition of properties after a certain interval is called periodicity of properties. If elements are arranged in increasing order of their atomic numbers, then elements repeat its properties after a definite interval this repression of properties is known as periodicity of properties.
(ii) Because the elements in a group have similar electronic configuration and thus, they have same number of valence electrons and therefore, they show similar chemical properties.
(iii) Atomic radius decreases in moving from left to right along a period. This is due to and increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom.