Question

Why do elements in the same group have similar physical and chemical properties?

Answer 1

Hint: The elements in the periodic table are arranged according to the Modern periodic law. It states that the physical and chemical properties of the elements are periodic functions of their atomic numbers. The physical and chemical properties depend on the number of valence electrons in an atom.

Complete step by step answer:
A vertical column in the periodic table of elements is called group. There are a total 18 groups present in the periodic table. In the basic theme of organisation of elements in the periodic table, elements having similar outer electronic configuration in their atoms are arranged in the same group. So, we should know that an element’s group number also denotes the number of electrons present in its outermost shell or valence shell. These valence electrons are responsible for the vast majority of physical properties, chemical properties and reactivities of the elements. If the valence shell electronic configuration remains the same within a group, physical and chemical properties tend to remain somewhat consistent.
So, we can say that elements in a group have the same physical and chemical properties because their atoms have the same number of valence electrons or same valence shell electronic configuration.

Note: The elements are classified into four groups named as s-block, p-block, d-block, and f-block depending on the type of atomic orbitals that are being filled with electrons. You can notice two exceptions to this categorization and they are: hydrogen and helium. It should be noted that properties of an element have periodic dependence upon its atomic number and not on relative atomic mass.