Я повесил ключи на крючок у двери, чтобы не искать их утром.

Повесил is the perfective past form, so it presents the action as completed: I hung up the keys.

Вешал would be imperfective, which could mean:

• the action was in progress,
• it happened repeatedly,
• or the result is not being emphasized.

In this sentence, the speaker means they did hang the keys on the hook, with the result that they would be easy to find later. That is why повесил is the natural choice.

Here ключи is accusative plural, the direct object of повесил.

For inanimate plural nouns in Russian, the accusative plural is usually the same as the nominative plural.

So:

• nominative: ключи = keys
• accusative: ключи = keys as a direct object

That is why the form does not change.

This is the classic Russian distinction between:

• motion toward a place → на + accusative
• location at a place → на + prepositional

So:

• повесил на крючок = hung onto the hook → movement toward the hook
• висят на крючке = are hanging on the hook → location

In this sentence, the action is about putting the keys onto the hook, so на крючок is correct.

У normally takes the genitive case, so двери here is genitive singular.

У двери means by the door / near the door.

So:

• крючок у двери = the hook by the door

This is a very common pattern:

• у окна = by the window
• у дома = by the house
• у входа = by the entrance

Both can mean near the door, but у двери is usually more natural and more common in everyday speech when something is right by something else.

• у двери = by the door, right at the door
• около двери = near the door, around the door area

In this sentence, крючок у двери sounds very natural, like a hook placed right by the door.

Because чтобы introduces a subordinate clause of purpose.

The second part explains why the speaker hung up the keys:

• Я повесил ключи на крючок у двери = main clause
• чтобы не искать их утром = purpose clause

Russian normally separates this kind of clause with a comma.

When the subject of both actions is the same person, Russian often uses:

• чтобы + infinitive

Here, the same person:

• hung up the keys,
• and did so in order not to search for them in the morning.

So:

• Я повесил ключи..., чтобы не искать их утром.

If the subject were different, Russian would usually use a finite verb instead:

• Я повесил ключи, чтобы он их не искал утром. = I hung up the keys so that he wouldn’t look for them in the morning.

Because искать means to look for / search for, while найти means to find.

The idea here is:

• I hung up the keys ... so that I wouldn’t have to look for them in the morning.

That is about the process of searching, not the final moment of finding them.

So:

• не искать = not have to search
• не найти would mean not to find, which would give a very different meaning

Because их is the accusative/genitive plural form of они, and here it is the direct object of искать.

• они = they (subject form)
• их = them (object form)

So:

• искать их = to look for them

This is exactly like English they vs them.

Утром is the instrumental case, and in many time expressions Russian uses the instrumental without a preposition.

So:

• утром = in the morning
• вечером = in the evening
• днём = during the day
• ночью = at night

This is just a standard adverbial time expression in Russian.

Yes. Russian word order is flexible, although different orders sound more or less natural depending on emphasis.

The original sentence is neutral and natural:

• Я повесил ключи на крючок у двери, чтобы не искать их утром.

Other possible orders:

• Ключи я повесил на крючок у двери, чтобы не искать их утром.
  This emphasizes the keys.
• Я повесил ключи у двери на крючок, чтобы не искать их утром.
  Also possible, though a bit less smooth.

Russian word order often reflects focus and emphasis, not just grammar.

Yes, very often you can.

Russian past tense verbs show gender and number, but not person. Even so, in context, повесил can often clearly mean I hung up if the subject is already understood.

So both are possible:

• Я повесил ключи... = explicitly I hung up the keys...
• Повесил ключи... = Hung up the keys... / I hung up the keys... in context

Including Я makes the subject explicit and can sound slightly more deliberate or contrastive.

In the past tense, Russian verbs are formed from the infinitive stem plus past-tense endings.

Повесил tells us:

• past tense
• singular
• masculine

Compare:

• повесил = he / I (if the speaker is male) hung up
• повесила = she / I (if the speaker is female) hung up
• повесило = it hung up
• повесили = they / you (plural, formal context-dependent) hung up

So if the speaker is female, the sentence would be:

• Я повесила ключи на крючок у двери, чтобы не искать их утром.

Yes, крючок means hook, especially a small hook on a wall or near a door.

So:

• на крючок = onto a hook

It is a very natural word in this context, especially for keys, a coat, or a bag.

A different word like вешалка usually means hanger or coat rack, so it would suggest a different object.