Relative clauses with 'que' (that/who/which), 'quien' (who/whom), 'lo que' (what/that which)

What are relative clauses?

A relative clause (in Spanish, una oración de relativo) is a clause that gives more information about a noun (the antecedent) or about an idea. In English we often use who, which, that, or what. In Spanish the most common relative pronouns are que, quien (quienes), and lo que. They connect the main clause to the extra information and tell you whether you mean a particular person/thing or an idea.

Examples:
- La chica que canta es mi hermana. — The girl who sings is my sister. (que links "la chica" with "canta")
- El libro que compré es interesante. — The book that I bought is interesting.
- No entiendo lo que dices. — I don't understand what you are saying. (lo que refers to the whole idea: "what you are saying")

Key terms
- Antecedent: the noun the relative clause refers to (e.g., "la chica", "el libro").
- Relative pronoun: word that starts the relative clause (que, quien, lo que).
- Restrictive (defining) clause: necessary to identify which person/thing.
- Nonrestrictive (non-defining) clause: extra information; usually set off by commas.

Using que

- que is the most common relative pronoun. It can refer to people or things and can be subject or object of the verb in the relative clause. It does not change for gender or number.

Examples (que as object and as subject):
- El libro que (obj.) leí era corto. — The book (that) I read was short.
- La mujer que (subj.) trabaja aquí es amable. — The woman who works here is kind.

Notes about que
- que often replaces who/which/that in English.
- In everyday Spanish, que is used very frequently even when other forms are possible.
- You normally cannot omit the relative pronoun in Spanish. Compare:
- English: The man I saw yesterday. — Spanish: El hombre que vi ayer. (Do not say: *El hombre vi ayer.)

- quien (singular) and quienes (plural) refer only to people. They are especially common after prepositions (a, con, de, para, en, etc.) and in nonrestrictive clauses (extra information set off by commas).

Examples:
- La mujer a quien llamaste es mi prima. — The woman whom you called is my cousin.
- Mi profesor, quien tiene mucha experiencia, nos explicó bien el tema. — My teacher, who has a lot of experience, explained the topic well.
- Los amigos quienes vinieron ayer son de Málaga. — The friends who came yesterday are from Málaga. (quienes is plural)

When to prefer quien
- After a preposition: Con quien hablé = with whom I spoke. You can also use con la que / con el que when referring to things.
- In nonrestrictive clauses about people: use quien (or el que/la que) after commas for clarity and formality.

Note: In many spoken contexts, que is used for people too (La mujer que llamó...), but in writing and formal speech, quien or el que/la que is often preferred after prepositions or in nonrestrictive clauses.

- lo que is neutral: it does not refer to a specific masculine or feminine noun. It refers to an idea, a fact, or an unspecified thing — in English: "what" or "that which." Use lo que when there is no clear antecedent.

Examples:
- No sé lo que quieres. — I don't know what you want.
- Lo que me preocupa es el dinero. — What worries me is the money.
- Lo que dijo Ana no fue verdad. — What Ana said was not true.

lo que vs. lo cual
- lo que: used when there is no explicit antecedent or when you mean "what/that which".
- Lo que necesito es descansar. — What I need is rest.
- lo cual: refers back to an idea or clause that was just mentioned; more formal and cannot stand alone without an antecedent.
- Llegó tarde, lo cual me molestó. — He arrived late, which bothered me.

Spanish, like English, distinguishes between clauses that define (restrictive/essential) and clauses that add extra information (nonrestrictive/non-essential). Commas and the choice of pronoun often change the meaning.

Examples showing meaning change:
- Los estudiantes que llegaron tarde perdieron la prueba. — The students who arrived late failed the test. (Only those who arrived late failed.)
- Los estudiantes, que llegaron tarde, perdieron la prueba. — The students, who arrived late, failed the test. (Implies all the students arrived late and they failed.)

Another pair:
- Mi hermano que vive en Madrid me visitará. — My brother who lives in Madrid will visit me. (You probably have more than one brother; you mean the one in Madrid.)
- Mi hermano, que vive en Madrid, me visitará. — My brother, who lives in Madrid, will visit me. (Extra information; you have one brother and he lives in Madrid.)

Pronouns and commas
- For people in nonrestrictive clauses (with commas), prefer quien/quienes or el que/la que/el cual, especially in formal writing: "Mi tía, quien vive cerca, vendrá." Many speakers still use que in conversation.

When the relative clause requires a preposition (because of the verb inside it or to express relationships), place the preposition before the relative pronoun.

Examples:
- La persona a quien escribí contestó. — The person to whom I wrote answered.
- La profesora con la que hablé es nueva. — The teacher with whom I spoke is new.
- La casa en la que vivo es pequeña. — The house in which I live is small.
- El libro del que te hablé está perdido. — The book I told you about is lost. (del = de + el)

Forms you can use after prepositions
- For people: a quien / con quien / de quien (or: el que / la que / los que / las que, or: el cual / la cual).
- El hombre con quien trabajo = El hombre con el que trabajo = El hombre con el cual trabajo.
- For things: preposition + el/la/los/las + que (en la que, por los que) or preposition + el/la/los/las + cual (more formal).

Personal "a"
- When a person is the direct object, Spanish usually uses the personal a: Vi a la chica que conociste. The relative pronoun can be que or a quien: La chica a quien conociste = the girl whom you met.

- You generally must include a relative pronoun in Spanish; omission (common in English) is not allowed: "El libro que leí" (not *El libro leí).
- Alternatives to que/quien/lo que:
- el que / la que / los que / las que: article + que — useful after prepositions and for clarity.
- El coche en el que viajé = the car in which I traveled.
- el cual / la cual: more formal and precise, used after prepositions.
- La razón por la cual vino fue distinta. (more formal)
- cuyo / cuya / cuyos / cuyas: expresses possession (whose).
- El autor, cuyo libro leí, es famoso. — The author, whose book I read, is famous.

When to choose which form
- que: everyday, works for people and things in most cases.
- quien(es): people, especially after prepositions or in nonrestrictive clauses.
- el/la que / el cual: use when the preposition needs an article or when you want extra clarity or formality.
- lo que / lo cual: refer to ideas or an unspecified thing; lo cual needs a previous explicit idea.

- Using lo que when a specific antecedent exists:
- Wrong: *La casa, lo que compré, es grande.
- Correct: La casa que compré es grande.

- Using quien for things (quien only for people):
- Wrong: *El libro quien me prestaste.
- Correct: El libro que me prestaste / El libro que me prestaste.

- Omitting the relative pronoun (unlike English):
- Wrong: *La chica conocí ayer.
- Correct: La chica que conocí ayer.

- Misplacing commas and changing the meaning accidentally — check whether the clause is essential or additional information.

- Confusing lo que and lo cual: remember lo que can introduce a clause without a clear antecedent; lo cual must refer to a previously mentioned idea.

- Use que for most relative clauses (people and things):
- El coche que compré es nuevo. — The car (that) I bought is new.
- Use quien(es) for people, especially after prepositions or in nonrestrictive clauses:
- El amigo a quien llamé respondió. — The friend I called answered.
- Use lo que for ideas or unspecified things ("what/that which"):
- Lo que dices no tiene sentido. — What you say doesn't make sense.
- Put commas for nonrestrictive extra information. For people in nonrestrictive clauses, prefer quien or el que/la que in formal writing:
- María, quien estudia medicina, vive aquí. — María, who studies medicine, lives here.
- After a preposition, put the preposition before the pronoun: con quien, en la que, por los que, del que.

- Relative clause (oración de relativo): A clause that adds information about a noun or idea.
- Antecedent: The noun or idea that the relative clause describes.
- Relative pronoun: Word that introduces the relative clause (que, quien, lo que, etc.).
- Restrictive (defining): Clause required to identify which thing/person.
- Nonrestrictive (non-defining): Clause that adds extra information; usually set off with commas.

- Start with que: it solves most cases and is widely used.
- Use quien/quienes for clarity after prepositions and for nonrestrictive (comma) clauses about people, especially in writing.
- Use lo que when you mean "what/that which" and there is no clear noun antecedent.
- Pay attention to commas: they often change meaning.

If you want, I can provide more example sentences grouped by tense, or short comparisons (que vs quien) with practice-style explanations (no exercises).