Question

The atomic number of an element ‘X’ is 16. In the modern periodic table element ‘X’ belongs to which period and group?

Answer 1

Modern periodic table was given by Mendeleev and was first published in 1869.
It is used to organise all the known elements according to their atomic number. There are 118 elements at present in the modern periodic table.
This table has 18 groups (vertical columns) and 7 periods (vertical rows) in which all the elements are arranged.
Most of the metals lie to the left of the periodic table and nonmetals to the left, they both are separated by a series of metalloids.
This periodic table is used to predict the trend of various properties of atoms according to their place assigned in the table.

Complete step by step answer:
As we are aware each element of this earth has a unique atomic number which can be used for their identification.
As you must be aware that atomic number is equal to the total number of electrons in an atom of that element and thus in element X there are 16 electrons in an atom
Let us learn how atomic number tells us about the group of that particular element:
The atomic number of X 16, thus the electronic configuration is ${\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{p}}^{\text{4}}}$ which means the last electron enters in p-orbital. Thus, element X is a p-block element.
Now, for p-block element group number is equal to the number of valence electrons+10 and therefore the group number of sulphur will be 6+10 = 16; (valence electrons are the number of electrons in the last subshell here it is with principal quantum number 3).
Let us now look at how to predict the period, the period of any given element is equal to the number of subshells here it 3. So the period for the given element will be third.
And thus the given element X with atomic number 16 is in group 16 and the third period of the modern periodic table.

Note: The element with atomic number 16 is Sulphur. Sulphur is a non-metal and is denoted with S. sulphur is found abundantly in earth's crust as pure element or sulphides or sulphate minerals, it is odourless and tasteless. In the native form sulphur is a crystalline solid which is yellow.