Question

Write the number of protons, electrons, and neutrons present in ${}_{19}{}^{39}\mathrm{K}$ element. Give the electronic configuration and draw the atomic diagram.

Answer 1

• Atom is represented with its symbol having an atomic number in subscript and mass number in superscript. Symbolic representation is mentioned below :

• For given element ${}_{19}{}^{39}\mathrm{K}$ :
• Part-1 Find number of protons, electrons and neutrons:
• The atomic number $\left(\mathrm{Z}\right)$ of an element is equal to the total number of protons present in the nucleus of the atom.
• $\mathrm{Atomic}\mathrm{number}=\mathrm{number}\mathrm{of}\mathrm{protons}=\mathrm{number}\mathrm{of}\mathrm{electrons}(\mathrm{for}\mathrm{electrically}\mathrm{neutral}\mathrm{atom})$
• The atomic number of potassium is $19$, so it has $19$ protons and hence number of electrons are also $19$.
• The mass number of elements is equal to the sum of the total number of protons and neutrons present in the nucleus of the atom.
• $\mathrm{Mass}\mathrm{number}=\mathrm{number}\mathrm{of}\mathrm{protons}+\mathrm{number}\mathrm{of}\mathrm{neutrons}$
• Also, $\mathrm{number}\mathrm{of}\mathrm{neutrons}=\mathrm{mass}\mathrm{number}-\mathrm{number}\mathrm{of}\mathrm{protons}$
• The number of neutrons in potassium$=$$35-17=18$.
• Therefore, potassium have $17$protons, $17$electrons and $18$ neutrons.
• Part-2 Electronic configuration
• Electronic configuration describes the distribution of electrons in different shells like $\mathrm{K},\mathrm{L},\mathrm{M},\mathrm{N}....$with principal quantum number $\left(\mathrm{n}\right)$ value $1,2,3,4...$respectively. According to formula$2{\mathrm{n}}^2$, maximum $2$ electrons can be filled in $\mathrm{K}$shell, $8$ in $\mathrm{L}$ and so on according to the formula. Therefore, an electronic configuration is $2,8,8,1$.

Shell	$\mathrm{K}$	$\mathrm{L}$	$\mathrm{M}$	$\mathrm{N}$
Number of electrons filled	$2$	$8$	$8$	$1$

• Part-3 Atomic Diagram: