Question

Show the formation of ${\text{N}}{{\text{a}}_{\text{2}}}{\text{O}}$ and ${\text{MgO}}$ by the transfer of electrons.

Answer 1

Hint: To answer this question we should know which atom donates electrons and which gains. How many electrons a donor atom donates and how many electrons an acceptor accepts to balance the total electrons of a molecule. For this, we should know the electronic configuration of each atom.

 Complete step by step answer:
${\text{N}}{{\text{a}}_{\text{2}}}{\text{O}}$ is known as sodium oxide. It is formed by electron transfer between sodium and oxygen.
Sodium is metal and oxygen is a non-metal. Sodium donates electrons and oxygen accepts electrons.

The electronic configuration of sodium metal is ${\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{s}}^1}$. The sodium metal has one valence electron. So, sodium can donate one electron to form a bond.

${\text{2}}\,{\text{Na}}\, \to 2\,{\text{N}}{{\text{a}}^{\text{ + }}}\, + \,2\,{{\text{e}}^ - }$

The electronic configuration of oxygen is ${\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^4}$ . The oxygen has four valence electrons. So, it requires two electrons to complete its octet, so it will accept two electrons.

${\text{O}}\, + \,2\,{{\text{e}}^ - } \to {{\text{O}}^{2 - }}\,$

So, oxygen will react with two sodium atom and form sodium oxide as follows:

$2\,{\text{N}}{{\text{a}}^{\text{ + }}}\, + \,{{\text{O}}^{2 - }}\, \ to \,{\text{N}}{{\text{a}}_{\text{2}}}{\text{O}}$

${\text{MgO}}$ is known as magnesium oxide. It is formed by electron transfer between magnesium and oxygen. Magnesium is metal and oxygen is a non-metal. Magnesium donates electrons and oxygen accepts electrons.

The electronic configuration of magnesium metal is ${\text{1}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{s}}^{\text{2}}}{\text{2}}{{\text{p}}^{\text{6}}}{\text{3}}{{\text{s}}^2}$. The magnesium metal has two valence electrons. So, magnesium can donate two-electron to form a bond.

${\text{Mg}} \to {\text{M}}{{\text{g}}^{{\text{2 + }}}}\, + \,2\,{{\text{e}}^ - }$

${\text{O}}\, + \,2\,{{\text{e}}^ - } \to {{\text{O}}^{2 - }}\,$

So, oxygen will react with one magnesium atom and form magnesium oxide as follows:

$\,{\text{M}}{{\text{g}}^{{\text{2 + }}}}\, + \,{{\text{O}}^{2 - }}\, \to \,{\text{MgO}}$

Therefore, ${\text{N}}{{\text{a}}_{\text{2}}}{\text{O}}$ forms by the transfer of two electrons from two sodium metals to oxygen and ${\text{MgO}}$ is forms by the transfer of two electrons from magnesium to oxygen.

Note: Metals are electropositive and non-metal are electronegative. Alkali or alkaline earth metal lies top left of the periodic table, and has the largest size, so they can donate electrons easily. After the donation of the electron, they get a stable fully-filled electronic configuration. Generally, an atom accepts or loses electrons to complete its octet. The outermost shell is known as the valence shell. During the formation of bonds, the outermost shell is used. The inner shell remains inactive generally.