Here's why:
* Subordinating conjunctions connect a dependent clause (which cannot stand alone as a sentence) to an independent clause (which can stand alone).
* "Whenever" introduces a dependent clause that expresses time or condition.
Example:
* Whenever I see you, I smile.
* "Whenever I see you" is the dependent clause.
* "I smile" is the independent clause.
Let me know if you have any other questions about conjunctions!