Question

Write the number of protons, electrons, and neutrons present in ${}_2{}^4\mathrm{He}$ 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 ${}_2{}^4\mathrm{He}$ :

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.

Atomic number = Number of protons = Number of electrons (for electrically neutral atom)

The atomic number of helium is $2$, so it has $2$ protons and hence number of electrons are also $2$.

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.

Mass number = Number of protons + Number of neutrons

Also, Number of neutrons = Mass number - Number of protons

The number of neutrons in helium $=$$4-2=2$.

Therefore, Helium have $2$ protons, $2$ electrons, and $2$ 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. Accordiong to formula $2{\mathrm{n}}^2$, maximum $2$ electrons can be filled in K shell. Therefore, an electronic configuration is $2,0$.

Part-3 Atomic Diagram: