Chapter U1.18, Problem 10E

Interpretation Introduction

Interpretation:

A common property or trend among the elements occurring in Period 3 of the periodic table needs to be explained.

Concept introduction:

The periodic table is a tabular arrangement of the known chemical elements where the elements are arranged according to their atomic numbers, electronic configurations and recurring periodic trends. Periodic trends are specific patterns in the properties of chemical elements such as electronegativity, atomic size, ionization potential, etc. The periodic trends arise from changes in the atomic structure and more specifically, the electronic configurations of the elements in the periods and the groups.

Answer to Problem 10E

The correct answer is the second option, option (B).

Explanation of Solution

Reason for correct option: It must be remembered that the elements in the periodic table are arranged in horizontal rows called periods and vertical columns called groups. The elements arranged in a particular period have the same number of atomic orbitals or electronic shells while the elements arranged in a particular group must have the same number of valence electrons.

Each electronic shell can hold a maximum number of electrons that is dictated by the 2n² rule where n is the number of the electronic shell. For example, n = 1 only has s subshell which can hold a maximum of 2 electrons as per the above rule. Similarly, for n = 3 there are s, p and d subshells which can together hold 18 electrons. All the elements whose outer electrons lie in a single shell will occur in a single period in the periodic table. Alternatively, all the elements of period 1 will have their electrons in the s subshell. Similarly, all the elements lying in period 2 must have s and p subshells.

Conclusion

Reason for incorrect options: The first option, option (A) is incorrect because the elements having the same number of valence electrons occur in a particular group of the periodic table and not a particular period.

The third option, option (C) is incorrect because the chemical properties of the elements depend on the number of valence electrons and hence, elements lying in a particular group in the periodic table will have similar chemical properties.

The last option, (D) is also incorrect.