Question

The element With atomic number belongs to Which period?
A. 2
B. 3
C. 4
D. 5

Answer 1

Hint: Before solving the problem, we have to know about the meaning of periods in the periodic table.
For a given atomic number, the valence shell electron number should be determined.
The valence shell number and the period number are related to each other.

Complete step by step answer:
The modern periodic table was proposed by Mendeleev and Moseley. All the elements in the periodic table are categorized by two ways: groups and periods. The vertical columns are named as groups and the horizontal rows are termed as periods. There are total 18groups and 7 periods in the periodic table.
According to the modern periodic table, the number of electronic shells or orbit is equal to the periodicity of a given element or atom. The electronic arrangement of various periods is 2,8,8,18,18,32,32.
The element with atomic number ₁₆ is Sulphur The number of electrons in various shells are 2,8,6 Here, the atom has three shells and the third shell has 6 valence electrons. As, there are 3 shells found in Sulphur, so, the periodicity is 3.

The answer is option (B)

Note:
The modern periodic table is arranged in terms of atomic number. The elements present in a common group have similar chemical properties. Each element in a period has one more electron than the previous element and their metallic character decreases along the period.