* Hydrogen (H): Hydrogen is a diatomic element, meaning it naturally exists as a molecule with two hydrogen atoms bonded together (H₂). So, a single molecule of hydrogen gas has 2 atoms.

* Chlorine (Cl): Chlorine is also a diatomic element, existing as Cl₂. Therefore, a single molecule of chlorine gas has 2 atoms.

To be specific:

* A hydrogen molecule (H₂) has 2 hydrogen atoms.

* A chlorine molecule (Cl₂) has 2 chlorine atoms.

Let me know if you'd like to know more about atoms or molecules!