Calcium Oxide (CaO) makes ionic bond while silicon (Si) makes covalent bond. By considering their atomic bonds, compare and discuss their properties given below. Electrical conductivity, Thermal conductivity, Melting point, Hardness,
Calcium Oxide (CaO) makes ionic bond while silicon (Si) makes covalent bond. By considering their atomic bonds, compare and discuss their properties given below.
Electrical conductivity,
Thermal conductivity,
Melting point,
Hardness,
The Correct Answer and Explanation is :
Calcium oxide (CaO) and silicon (Si) have distinct atomic structures, leading to different properties due to the nature of their bonds. CaO forms ionic bonds, while Si forms covalent bonds, and these differences impact their electrical conductivity, thermal conductivity, melting point, and hardness.
Electrical Conductivity:
- Calcium Oxide (CaO): Being an ionic compound, CaO conducts electricity in molten state or when dissolved in water. In solid form, however, it does not conduct electricity because the ions are not free to move.
- Silicon (Si): Silicon, being a covalent solid, does not conduct electricity well in any state. Its covalent bonds restrict the free movement of electrons, making it a poor conductor. However, silicon becomes a semiconductor when doped with impurities, allowing it to conduct under specific conditions.
Thermal Conductivity:
- Calcium Oxide (CaO): As an ionic compound, CaO has good thermal conductivity. The ions in the lattice structure can transfer energy effectively, making it a good heat conductor.
- Silicon (Si): Silicon has lower thermal conductivity compared to ionic compounds like CaO. The covalent bonds in silicon create more localized electron movement, which reduces its ability to transfer heat efficiently.
Melting Point:
- Calcium Oxide (CaO): CaO has a high melting point, around 2,572°C, because of the strong electrostatic forces between the positively charged calcium ions (Ca²⁺) and the negatively charged oxide ions (O²⁻) in its ionic lattice.
- Silicon (Si): Silicon also has a high melting point, approximately 1,414°C, but lower than CaO. The covalent bonds in silicon are strong, but ionic bonds are generally stronger due to their electrostatic nature.
Hardness:
- Calcium Oxide (CaO): Calcium oxide is relatively hard due to the strong ionic bonds, but it is also brittle. The ionic lattice does not easily absorb stress, causing the crystal structure to break under pressure.
- Silicon (Si): Silicon is harder than many metals due to its covalent bonding, which forms a rigid network of atoms. However, like CaO, silicon is also brittle and can fracture under high pressure.
Conclusion:
In summary, the properties of CaO and Si are influenced by the nature of their bonds. Ionic bonds in CaO give it good electrical and thermal conductivity, a very high melting point, and hardness but also make it brittle. In contrast, the covalent bonds in silicon result in poor electrical and thermal conductivity, a lower melting point, but greater structural rigidity, making it harder yet still brittle.