Question

$\left(\mathrm{i}\right)$Write the electron dot structure for sodium and oxygen.

$\left(\mathrm{ii}\right)$ Show the formation of ${\mathrm{Na}}_2\mathrm{O}$ and $\mathrm{MgO}$ by electron transfer of electrons.

$\left(\mathrm{iii}\right)$ What are the ions present in these compounds?

Answer 1

Electron dot structure:

1. The chemical bonding between atoms in a molecule is depicted by an electron dot structure. They also show the total number of lone pairs in each of the molecule's atoms.
2. Sodium has an atomic number$=11$, and its electronic configuration$=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$ hence, valence electron$=1$
3. Oxygen has an atomic number$=8$, and its electronic configuration $=1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$ hence valence electron$=6$
4. Arranging the valence electron around the atom we get their lewis dot structure.

Formation of ${\mathrm{Na}}_2\mathrm{O}$ and $\mathrm{MgO}$

1. In Sodium oxide, electronic configuration of Sodium with atomic number$=11$ is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^1$, hence its valence electron$=1$
2. Electronic configuration of Oxygen with atomic number$=8$ is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$, hence its valence electrons$=6$
3. Although Sodium only has one additional electron, oxygen requires two-electron to be stable. As a result, if two Sodium atoms share one electron, Oxygen can receive two electrons.
4. The two Sodium atoms generate Sodium ions ($2{\mathrm{Na}}^{+}$) by losing two electrons. The Oxygen atom gains two electrons and produces an oxide ion (${\mathrm{O}}^{2-}$).
5. Therefore, the octet of Oxygen is completed.
6. In Magnesium oxide compound, Electronic configuration of Magnesium with atomic number$=12$ is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^2$ hence its valence electrons$=2$
7. Electronic configuration of Oxygen with atomic number$=8$ is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^4$ hence its valence electrons$=6$
8. Similarly in the Magnesium oxide compound, Magnesium gives 2 electrons to oxygen and becomes ${\mathrm{Mg}}^{+2}$. And oxygen becomes ${\mathrm{O}}^{2-}$ due to the gain of electrons.
9. Therefore, the octet of Oxygen is completed.

Ionic Compounds:

1. Negatively charged anions combine with positively charged cations to generate ionic compounds, which are electrically neutral.
2. In Sodium oxide (${\mathrm{Na}}_2\mathrm{O}$) ions present are $2{\mathrm{Na}}^{+}$and ${\mathrm{O}}^{2-}$
3. In Magnesium oxide ($\mathrm{MgO}$) ions present are ${\mathrm{Mg}}^{+2}$ and ${\mathrm{O}}^{2-}$