Question

The element with the atomic number 12 belongs to the ____ group and _____ period.

Answer 1

Hint: An attempt to solve this question can be by writing down the electronic configuration of the element to get a clear idea of the valency, number of valence electrons as well as group number and period number.

Complete step-by-step answer:
Let us write down the electronic configuration (e.c.) of the element whose atomic number (Z) =15.
Electronic configuration of Z=12 is,
$1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}}$
From this we get to know that there are already 2 electrons in the last/valent shell, hence the number of valence electrons is 2.
Valency is defined as the number or electrons that need to be gained or lost in order to gain maximum stability of the radical. Since there are 2 electrons present, the atom will release 2 electrons to gain complete octet configuration.
The highest principal quantum number in which the electrons are present for the element with atomic number(Z=12) is 3. The period of the element is 3.
There are 18 groups in the periodic table and the 18th group consists of noble gases which have a complete valence shell (also called octet). The element of our discussion releases 2 electrons to gain maximum stability. So, the group number becomes 2. Group 2 of the periodic table is also called the 2A group.

Hence the group number of the element with atomic number(Z)= 12 is 2A and the period number is 3.

Note: Remember to fill electrons in increasing order of their energy. Electronic configuration is written in accordance with Aufbau principle only.