Se o técnico chegar hoje, eu vou avisar você imediatamente.

Because after se when you are talking about a possible future situation, Portuguese normally uses the future subjunctive.

So:

• Se o técnico chegar hoje... = if the technician arrives today...
• Se o técnico chega hoje... sounds wrong for this meaning in standard Portuguese.

This is a very common pattern:

• Se eu tiver tempo, eu vou.
• Se ela puder, ela ajuda.
• Se eles chegarem cedo, começamos.

For English speakers, this feels unusual because English uses the present after if: if he arrives. Portuguese often uses the future subjunctive instead.

Here chegar is the future subjunctive form of the verb chegar.

For many -ar verbs, the eu form of the future subjunctive looks identical to the infinitive, so it can be confusing.

For chegar, the future subjunctive forms are:

• se eu chegar
• se você/ele/ela chegar
• se nós chegarmos
• se vocês/eles/elas chegarem

So in this sentence, chegar is not just the dictionary form by coincidence; it is the correct conjugated form for o técnico.

A very common use is for future or uncertain events introduced by words like:

• se = if
• quando = when
• assim que = as soon as
• logo que = as soon as
• caso = in case

Examples:

• Se ele vier, eu falo com ele.
• Quando você chegar, me liga.
• Assim que o técnico terminar, eu aviso.

In this sentence, the technician has not arrived yet, so the action is still in the future and uncertain. That is why chegar is in the future subjunctive.

Both are possible, but eu vou avisar is much more common in everyday Brazilian Portuguese.

• Eu vou avisar você imediatamente. = natural, common in speech
• Avisarei você imediatamente. = correct, but more formal or written

Brazilian Portuguese often prefers ir + infinitive for the future, especially in conversation.

So:

• vou avisar = everyday future
• avisarei = simple future, often more formal

Yes. Portuguese often drops subject pronouns when the meaning is clear.

So these both work:

• Se o técnico chegar hoje, vou avisar você imediatamente.
• Se o técnico chegar hoje, eu vou avisar você imediatamente.

Including eu can add slight emphasis or clarity, but it is not required.

Portuguese uses definite articles more often than English.

So o técnico often means:

• the technician
• sometimes even the technician we are expecting / the technician in question

In English, we might say if the technician arrives today or sometimes just if technician arrives would be impossible. In Portuguese, o técnico is the natural choice when referring to a specific expected person.

Without the article, técnico would usually not sound natural here.

In this sentence, técnico most likely means technician or repair technician.

Depending on context, técnico can also mean:

• a technical specialist
• a coach, especially in sports
• someone with technical training

But in a sentence like this, native speakers will often understand it as someone coming to fix, install, inspect, or service something.

Yes. In Brazilian Portuguese, te avisar is very common and often sounds more natural in conversation.

Possible versions:

• vou avisar você = correct, clear, neutral
• vou te avisar = very common in Brazil, especially in speech
• avisá-lo = correct, but more formal and less common in everyday spoken Brazilian Portuguese

So all of these can work:

• Se o técnico chegar hoje, eu vou avisar você imediatamente.
• Se o técnico chegar hoje, eu vou te avisar imediatamente.

For learners, te avisar is worth recognizing because you will hear it a lot.

Not exactly.

• avisar usually means to let someone know, to warn, or to tell someone
• informar is usually more formal and often means to inform

In this sentence, avisar is the natural everyday verb:

• vou avisar você = I’ll let you know / I’ll tell you

Using informar here would sound more formal and less conversational.

Yes, adverbs like imediatamente can often move around, though some positions sound more natural than others.

Natural options include:

• Eu vou avisar você imediatamente.
• Eu vou imediatamente avisar você.
• Imediatamente, eu vou avisar você. (more emphatic or stylistic)

The original version is the most neutral and natural in everyday speech.

At the end, imediatamente clearly modifies avisar: I’ll notify you immediately.

No. That word order is not correct.

In Portuguese, with a normal verb phrase like this, the object comes after the infinitive:

• vou avisar você

Or you use an object pronoun:

• vou te avisar

So the correct patterns are:

• eu vou avisar você
• eu vou te avisar

Not:

• eu vou você avisar

Yes, depending on the nuance.

Portuguese often uses the present tense to talk about the near future. So:

• Se o técnico chegar hoje, eu te aviso imediatamente.

This is very natural in Brazilian Portuguese.

Compare:

• eu vou avisar você = I’m going to let you know
• eu te aviso = I’ll let you know

Both are common. The present tense future meaning is especially frequent in speech.

Because the sentence begins with a conditional clause:

• Se o técnico chegar hoje = if the technician arrives today

Then comes the main clause:

• eu vou avisar você imediatamente

In Portuguese, it is standard to separate an initial subordinate clause from the main clause with a comma.

So the structure is:

• [conditional clause], [main clause]

The accent in técnico shows the stressed syllable:

• TÉC-ni-co

The stress falls on the first syllable.

The é is an open e sound. For an English speaker, a rough approximation is:

• TEH-nee-koo

Also notice:

• chegar has stress on the last syllable: che-GAR
• imediatamente is longer and usually stressed on a-men: i-me-di-a-ta-MEN-te

The accent mark is important because it tells you where the stress goes and sometimes what vowel quality to use.

Yes, but the original position is very natural.

Common options:

• Se o técnico chegar hoje, eu vou avisar você imediatamente.
• Se hoje o técnico chegar, eu vou avisar você imediatamente.
  This is possible, but it sounds more marked or literary.
• Eu vou avisar você imediatamente se o técnico chegar hoje.
  Also correct, but now the conditional clause comes at the end.

Putting hoje right after chegar is straightforward and natural.

It is mostly neutral.

• Se o técnico chegar hoje = neutral
• eu vou avisar = common, everyday Brazilian Portuguese
• você = neutral in many parts of Brazil

If you wanted it to sound more conversational in Brazil, you might hear:

• Se o técnico chegar hoje, eu vou te avisar imediatamente.

If you wanted it more formal, you might see:

• Se o técnico chegar hoje, avisarei imediatamente.

So the original sentence is correct and natural, with a neutral tone.