Here's why:
* Elements are the simplest pure substances that cannot be broken down further by chemical means. They exist in their elemental state as individual atoms.
* Molecules are formed when two or more atoms bond together. For example, oxygen gas (O2) is a molecule.
* Ionic compounds are formed when a metal (like calcium) reacts with a non-metal. The metal loses electrons to become a positively charged ion (cation) and the non-metal gains electrons to become a negatively charged ion (anion). These oppositely charged ions then attract each other, forming an ionic bond.
In summary: Calcium exists as individual calcium atoms in its elemental state. It only forms ionic compounds when it reacts with other elements.
