Learn Hardcore Japanese: eki ni tuitara, haha ni renrakusimasu. - When I arrive at the station, I will contact my mother.

The particle に marks the destination or point at which an action occurs. With 着く (to arrive), 駅に着く literally means “arrive at the station.” So 駅に着いたら means “when/once (I) arrive at the station.”

How does the ～たら form in 着いたら work? What nuance does it add?

The ～たら form is a conditional made by attaching ら to the past tense stem (the た form). It expresses “when/after” something happens (or “if,” in other contexts). Here, 駅に着いたら = “once I arrive at the station,” emphasizing sequence: first arrival, then the next action.

Why is 母に連絡します using に instead of を?

The verb 連絡する takes the person you contact as an indirect object, marked by に. It’s like saying “to contact someone,” so 母に連絡します means “I will contact my mother.”

What’s the difference between 連絡する and 電話する? Can I say 母に電話します here?

電話する specifically means “to make a phone call,” while 連絡する means “to get in touch/contact” more generally (phone, email, SMS, etc.). Yes, you can say 母に電話します if you want to stress that you’ll call her by phone. 連絡します keeps it neutral.

Why is it 母 and not お母さん in this sentence?

Both are acceptable. 母 is a plain, neutral term for “mother” when speaking about your own mom. お母さん is more polite or affectionate and also used when talking about someone else’s mother. You could easily say お母さんに連絡します to soften or polite-up the tone.

There’s no subject like 私は. Is that okay?

Yes. Japanese commonly omits the subject when it’s clear from context. Here, it’s understood that the speaker is the one arriving and calling, so 私は is unnecessary.

When should I use ～たら versus ～と for “when” or “if”?

Use ～たら for one-time or future events and to express an intentional action in the main clause (“When I X, I will Y”). Use ～と for natural consequences or habitual truths, and you cannot follow ～と with a volitional or planned result. E.g.:

駅に着いたら連絡します (“I’ll contact you when I arrive at the station.”)
ボタンを押すとドアが開く (“If/whenever you press the button, the door opens.”)

How polite is 駅に着いたら、母に連絡します? Is it casual or formal?

This sentence is neutral-to-polite because of the –ます form in 連絡します. It’s fine for everyday conversation with acquaintances or your family. For casual speech among close friends, you could drop –ます: 駅に着いたら、母に連絡する. For extra formality, you might use 着きましたら or add honorifics elsewhere, but that’s uncommon here.

What’s the comma after 着いたら for? Is it necessary?

The comma (読点) indicates a slight pause between the conditional clause and the main clause, making the sentence easier to read or hear. It’s not strictly required in short sentences, but it’s common to separate complex or multi-clause sentences for clarity.