Question

The pair of elements that have similar chemical properties are:
A. Lithium and Magnesium
B. Beryllium and Boron
C. Aluminium and Magnesium
D. Carbon and Nitrogen

Answer 1

Hint: Columns in the periodic table are called groups or family because of their similar chemical behavior. All the members of a group of elements have the same number of valence electrons and similar chemical properties.


Complete step by step answer:
Now from the question
We are given the following elements Lithium , Magnesium , Beryllium, Boron, Aluminium ,Carbon ,Nitrogen .Now when we arrange them according to their position in the periodic table :
3Li, 4Be, 5B, 6C, 7N, 12Mg, 13Al
We notice that Li, Be, B, C, N are in the 2 period and Mg , Al lie in the 3 period and elements in the periods chemical properties are not the same. The elements of the same group have similar chemical properties because they have the same number of valence electrons.The given elements are not from the same groups.
But a diagonal relationship exists between certain pairs of diagonally adjacent elements in the second and third periods. These are the first 20 elements in the periodic table. For example, pairs lithium (Li) and magnesium (Mg), beryllium (Be) and aluminium (Al), boron (B) and silicon (Si), etc are exhibiting similar properties. Boron and Silicon are both semiconductors.
The given elements are also from the 2nd and 3rd period but they are already given to us in pairs and out these 4 pairs only Li and Mg are the pairs which are diagonal pairs
Thus Magnesium and Lithium have similar properties.
So, the correct answer is “Option A”.

Note: It is found that the chemistry of a first-group (second period) element often has similarities to the chemistry of the second-group (third period) element one column to the right of it in the periodic table. Thus, the chemical properties of Li have similarities to that of Mg, the chemistry of Be has similarities to that of Al, and the chemistry of B has similarities to that of Si. These are called diagonal relationships. The reasons for the existence of diagonal relationships are not fully understood, but charge density is a factor.