The infinitive is to eat; the past tense is ate; the past participle is eaten; the present participle is eating.
"to eat" is an infinitive.
"Am" is the first person singular present indicative form of "to be", for which the past participle is "been". Fundamentally, only infinitive verbs have past participle's; therefore "am", which can not be a proper infinitive, does not have any past participle.
infinitive: be past: was/were past participle: been
"Am" is the first person singular present indicative form of "to be", for which the past participle is "been". Fundamentally, only infinitive verbs have past participle's; therefore "am", which can not be a proper infinitive, does not have any past participle.
infinitive: break past: broke past participle: broken
infinitive: swim past: swam past participle: swum
infinitive: run past: ran past participle: run
infinitive: throw past: threw past participle: thrown
infinitive: throw past: threw past participle: thrown
infinitive: creep past: crept past participle: crept
infinitive: throw past: threw past participle: thrown
infinitive: freeze past: froze past participle: frozen