Question

Write the electronic configuration of ${}_{14}{}^{28}\mathrm{Si}$ and hence its valency as well as the formulae of its chlorides and oxides.

Answer 1

• Given the atomic number of silicon is 14.
• Atomic number is the number of protons in an atom.
• In an electrically neutral atom, the number of electrons and protons are equal. Hence silicon will have 14 electrons.
• Electronic configuration is the arrangement of electrons in different energy levels around the atom.
• Thus the electronic configuration: 2,8,4. Since it has 4 electrons in the outermost shell, the valency is 4. It needs 4 more electrons to complete its octet.

Chloride:

• Chlorine has 17 electrons and the electronic configuration: 2,8,7. It has one electron less than the stable electronic configuration.
• Thus one silicon atom and 4 chlorine atoms can combine together to form a silicon chloride molecule (${\mathrm{SiCl}}_4$).
• Hence each chlorine atom shares one electron with one silicon atom. Thus the valency of silicon and chlorine are satisfied.

Oxide:

• Oxygen atom has 8 electrons and the electronic configuration:2,6. It has two electrons to complete an octet.
• Thus two oxygen atoms and one silicon atom can combine together to form silicon dioxide molecules (${\mathrm{SiO}}_2$).
• Here each oxygen atom shares two electrons with the silicon atom. Thus both silicon and oxygen can complete their octet.