Question

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

Answer 1

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.