Answer:
Adverb
Step-by-step explanation:
Hullo :D
Remember that most adverbs end in -ly. In your case, the word, Impatiently, ends in -ly.
Adverbs tell when, where, and how. Impatiently tells HOW the toddler waited.
Therefore, it is an
.
EDIT: It also depends on the context. Impatiently can be an adjective as well. I may have interperted it wrong D:
Hope this helps!!