Question

The electronic structure (configuration) of fluorine atom can be written as $2,7$. In a similar way, give the electronic configuration of aluminium.

Answer 1

• Electronic configuration describes the distribution of electrons in different shells like $\mathrm{K},\mathrm{L},\mathrm{M},\mathrm{N}....$with principal quantum number $\left(\mathrm{n}\right)$ values $1,2,3,4...$respectively.
• According to the formula$2{\mathrm{n}}^2$, maximum $2$ electrons can be filled in $\mathrm{K}$shell, $8$electrons in $\mathrm{L}$shell, $18$electrons in the $\mathrm{M}$shell and so on.
• According to octet rule, atoms can combine either by transfer of valence electrons from one atom to another or by sharing their valence electrons in order to attain the nearest noble gas configuration by having $8$electrons in their valence shell.

• The atomic number of aluminium is $13$.
• The atomic number is determined by the total number of protons present in the nucleus of the atom.
• The number of protons are equal to the number of electrons to maintain the electrical neutrality of the atom, i.e. number of electrons are$13$.
• Hence, the electrons are distributed in different shells as $2$electrons in $\mathrm{K}$shell, $8$electrons in $\mathrm{L}$shell, and remaining $3$electrons in the $\mathrm{M}$shell giving electronic configuration$2,8,3$.