Question

Complete the following:

Symbol	Atomic number	Mass number	Protons	Neutrons	Electrons	Electronic configuration
Argon ${}_{18}{}^{40}\mathrm{Ar}$

Answer 1

• Atomic number(Z)- The total number of protons in the nucleus of an atom gives us the atomic number of that atom.
• Mass number(A)- The number of protons and neutrons combine to give us the mass number of an atom.
• The electronic configuration of an element describes how electrons are distributed in its atomic orbitals.
• The electrons are filled in the increasing number of shells viz. K,L,M,N,etc.
• The atoms are written in this manner ${}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}$ where A denotes mass number and Z denotes the atomic number.
• Any neutral atom has the same number of electrons as the number of electrons.
• For a neutral atom Z=atomic number=number of protons=number of electrons.
• Number of neutrons=A-Z
• Hence, the completed table will be-

Symbol	Atomic number	Mass number	Protons	Neutrons	Electrons	Electronic configuration
Argon ${}_{18}{}^{40}\mathrm{Ar}$	18	40	18	22	18	2,8,8