O professor com quem eu quero conversar ainda não chegou.

Because the verb conversar normally takes the preposition com when you say who you are talking with:

• conversar com alguém = to talk with/to someone

So in a relative clause, Portuguese keeps that preposition:

• o professor com quem eu quero conversar

Literally, this is something like the professor with whom I want to talk.

In standard Portuguese, this is the normal structure.

Because conversar needs com before the person.

So you cannot normally say:

• quem eu quero conversar
• que eu quero conversar

in careful standard Portuguese, because the preposition is missing.

The standard options are:

• o professor com quem eu quero conversar
• o professor com o qual eu quero conversar (more formal)

In very informal Brazilian Portuguese, you may hear:

• o professor que eu quero conversar com

That is common in speech, but it is less formal than com quem.

Portuguese normally does not leave the preposition at the end in standard grammar.

English can do this:

• the professor I want to talk to

Portuguese usually prefers:

• o professor com quem eu quero conversar

So the preposition stays attached to the relative pronoun.

This is one of the most noticeable differences between English and Portuguese relative clauses.

Yes.

You can say:

• O professor com quem eu quero conversar...
• O professor com o qual eu quero conversar...

Both are grammatical.

The difference is mainly style:

• com quem sounds more natural and common for people
• com o qual sounds more formal, heavier, and a bit more written

For everyday Brazilian Portuguese, com quem is usually the better choice here.

Yes, it could be omitted.

Portuguese often drops subject pronouns when the verb ending already shows the subject:

• com quem quero conversar
• com quem eu quero conversar

Both are correct.

Including eu can add a little clarity or emphasis, but it is not required here.

Because after querer when it is followed by another action, Portuguese normally uses the infinitive:

• quero conversar = I want to talk
• quero comer = I want to eat
• quero sair = I want to leave

So:

• eu quero conversar

is the standard pattern: querer + infinitive.

It means hasn’t arrived yet or still hasn’t arrived.

Here, ainda with não gives the idea of yet/still in a negative sentence:

• ainda não chegou = has not arrived yet / still hasn’t arrived

Compare:

• já chegou = has already arrived
• ainda não chegou = hasn’t arrived yet

So ainda does not literally mean only still here; with negation, it often corresponds to English yet.

Because Portuguese usually uses the simple past form chegou in contexts where English often uses the present perfect:

• Ele ainda não chegou. = He hasn’t arrived yet.

This is very normal in Portuguese.

Using tem chegado would usually suggest repeated or ongoing arrival in certain contexts, not the simple idea of has arrived / hasn’t arrived yet.

So for arrival at a specific moment, chegou is the natural choice.

Yes, word order can vary a bit.

The most neutral version is:

• ainda não chegou

You can also hear:

• não chegou ainda

Both are common in Brazilian Portuguese.

A rough comparison:

• ainda não chegou = very standard, neutral
• não chegou ainda = also natural, often a bit more conversational

In your sentence, ainda não chegou sounds completely normal.

It is a relative clause describing o professor.

Main noun:

• o professor

Relative clause describing which professor:

• com quem eu quero conversar

So the whole sentence means:

• The professor [with whom I want to talk] hasn’t arrived yet.

This relative clause helps identify the professor more specifically.

Yes.

• o professor = the male professor / the professor (masculine form)
• a professora = the female professor

So if the person were female, the sentence would be:

• A professora com quem eu quero conversar ainda não chegou.

Notice that chegou stays the same; the past form does not change for gender here.