Calcium oxide is an ionic compound. (True or false) If false, then what is the right answer?
The correct answer and explanation is:
True.
Calcium oxide (CaO) is indeed an ionic compound. It is composed of calcium ions (Ca²⁺) and oxide ions (O²⁻), held together by strong electrostatic forces of attraction in a regular repeating pattern known as a crystal lattice. The ionic nature of calcium oxide comes from the way the atoms interact to form ions.
Calcium (Ca) is an alkaline earth metal with an atomic number of 20. In its elemental form, calcium has two electrons in its outermost shell. Because calcium is relatively electropositive, it readily loses these two electrons to achieve a stable electron configuration, forming a Ca²⁺ ion. On the other hand, oxygen (O) is a nonmetal with an atomic number of 8. Oxygen has six electrons in its outer shell and needs two more to complete its octet. Therefore, oxygen tends to gain two electrons, forming an O²⁻ ion.
When calcium and oxygen react to form calcium oxide, calcium donates its two electrons to oxygen, creating two oppositely charged ions: Ca²⁺ and O²⁻. The positive charge on the calcium ion and the negative charge on the oxide ion result in a strong electrostatic attraction, forming the ionic bond. The result is a stable ionic compound, calcium oxide (CaO).
The ionic nature of calcium oxide gives it certain properties. It has a high melting point because of the strong forces between the oppositely charged ions. It also tends to dissolve in water, forming a strong alkaline solution known as calcium hydroxide (Ca(OH)₂). This is consistent with the behavior of many ionic compounds that dissolve in water and dissociate into their constituent ions.
Thus, the classification of calcium oxide as an ionic compound is accurate.