Question

Write the complete symbol for the atoms with given atomic and mass no, $Z = 18$ $A = 40$ and $A = 9$ ( $Z =$ Atomic no. and $A =$ mass).

Answer 1

The complete symbol of the element can be defined by the number of fundamental elements that are present in the atom. The atomic number, as well as the mass number of the atom, are based on these fundamental elements that are part of the atom of an element.

Complete step by step solution
The complete atomic number of this particular element is $18$ which means that the number of electrons or the number of protons of the specific atom of the element is $18$ . The mass of the specific element is $40$ which defines all the nucleons in the specific atom. The nucleons of a specific atom are the total number of protons and the neutrons that are present in the nucleus of the specific atom. Therefore, the element in the modern periodic table having the atomic number of the $18$ is Argon. This is because the total number of electrons present in an atom is $18$ means that the electronic configuration is $2,8,8$ according to the number of shells filled by electrons. The valence shell of this element contains $8$ electrons which prove that the element is an inert element as the valence is filled till octet configuration. The Argon is the inert gas which is present as the element with the given number of fundamental elements. The symbol of Argon as the inert element with the specific number of electrons, protons and neutrons is $Ar$ .

Note
The importance of electronic configuration is important because it can define the atomic number of the element and it becomes easier to detect the position of the element in the periodic table. This helps in defining the characteristics of the element and how it reacts and interacts.