Question

An element with electronic configuration 2, 8, 2 belongs to which period and group?
A.2, 3
B.4, 3
C.2, 1
D.3, 2

Answer 1

To answer this question, you should recall the formation of the periodic table. According to modern periodic law states that, the physical and chemical properties of elements are the periodic function of their atomic number. From the number of shells and number of valence electrons we can find the period and group number.

Complete Step by step solution:
We know that the modern periodic table is based on the atomic number of elements. Atomic number (Z) is equal to the number of protons present in the nucleus of an atom of an element. The modern periodic table contains 18 vertical columns known as a group and seven horizontal rows known as periods. The elements of a same group of the periodic table have the characteristic feature that they have the same number of valence electrons.
The electronic configuration of the element is 2,8,2 as given in the question. We can write electronic configuration as $\left[ {{\text{Ne}}} \right]{\text{3}}{{\text{s}}^{\text{2}}}$ . The valence electrons that are 2 are equal to the group number.
The no. of shells, that are 3 is equal to the period no. For this element, the no. of valence electrons =2, valency =2 and as it is metal it belongs to the s-block. The element which belongs to the 3rd period and group 2 is Magnesium. Therefore, we can conclude that the correct answer to this question is option D.

Note: There are 4 blocks in the periodic table: s-block, p-block, d-block and f-block. All of the s-block elements are metals. Usually, they are shiny, silvery, good conductors of heat and electricity, and lose their valence electrons easily. The p-block has the biggest variety of elements and is the only block that contains three types of elements: metals, nonmetals and metalloids. d-block elements have properties that are between s-block elements and p-block elements properties. It consists of transition metals. The f-block elements are mostly radioactive. The block names were created to represent the quality of the spectroscopic lines of the atomic orbitals.