the particle "if" assumes several functions in the Portuguese language:
1- Conjunction:
a) Integral subordinate conjunction: the conjunction introduces substantive subordinate clauses.
Ex: I want to know if she will come to the party.
b) Conditional Subordinate Conjunction: introduces conditional adverbial subordinate clauses.
Ex: Leave a message if you don't find me.
2- Pronoun:
a) Reflective pronoun: works as a direct object, indirect object and subject of the infinitive.
E.g.: The child hurt-if. (direct object)
b) Passive particle: when it is linked to direct transitive verbs with the intention of passing them on.
E.g.:if strange stories.
c) Subject indeterminacy index: when it is linked to prepositioned verbs with the role of indetermining the subject.
Ex: Disagree-if of fact.
d) Expletive particle: does not perform any syntactic function when associating with verbs.
Ex: He just sat-if.
e) Integral particle of the verb: linked to pronominal verbs.
Ex: She can't get enough of complaining-if.
By Marina Cabral
Specialist in Portuguese Language and Literature
Brazil School Team
Grammar - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/gramatica/funcoes-particula-se.htm