Here's why:

* Chemical combination: This means that the elements are not just physically mixed together, but their atoms are actually rearranging and bonding to form a new substance with different properties.

* New substance: The compound has properties that are distinct from the original elements. For example, water (H₂O) is a liquid at room temperature, while hydrogen (H₂) and oxygen (O₂) are both gases.

Here are some examples of compounds:

* Water (H₂O): Formed from hydrogen and oxygen.

* Table salt (NaCl): Formed from sodium and chlorine.

* Carbon dioxide (CO₂) : Formed from carbon and oxygen.

Let me know if you'd like more examples or want to delve deeper into the chemical bonding process!