* Calcium (Ca) has two electrons in its outermost shell. These electrons are relatively loosely bound and are easily lost.
* Oxygen (O) needs two more electrons to complete its outermost shell. It has a strong attraction for electrons.
* When calcium and oxygen react, calcium loses its two outer shell electrons. This creates a positively charged calcium ion (Ca²⁺).
* The oxygen atom gains these two electrons. This creates a negatively charged oxide ion (O²⁻).
* The opposite charges attract, forming an ionic bond. The resulting compound is calcium oxide (CaO).
In summary: The outer shell electrons of calcium are transferred to oxygen atoms, resulting in the formation of ions and an ionic compound.
