Ég heimsæki ömmu mína á morgun.

Because heimsæki is the conjugated form, while heimsækja is the infinitive.

In this sentence, the subject is ég, so the verb has to match 1st person singular present:

• ég heimsæki = I visit
• þú heimsækir = you visit
• við heimsækjum = we visit

So after ég, you need heimsæki, not heimsækja.

That is very normal in Icelandic. A present-tense form is often used for a future meaning when a time expression makes the timing clear.

Here, á morgun tells you the action happens in the future, so heimsæki is understood as will visit.

This is similar to English patterns like:

• I am visiting my grandma tomorrow
• We leave tomorrow

So Icelandic does not need a separate word like will here.

Because amma changes form here due to case.

The verb heimsækja takes a direct object, and that object is in the accusative case.
The accusative singular of amma is ömmu.

So:

• amma = nominative, the basic form
• ömmu = accusative, used here as the object of heimsæki

This is one of the most important things English speakers have to get used to in Icelandic: nouns often change form depending on their role in the sentence.

Because the possessive has to agree with the noun it describes.

Here, mína refers to ömmu, and ömmu is:

• feminine
• singular
• accusative

So the possessive must also be feminine singular accusative, which gives mína.

Compare:

• amma mín = my grandma, nominative
• ömmu mína = my grandma, accusative

So the change from mín to mína is not random. It matches the grammar of ömmu.

Because that is a very common Icelandic pattern.

In Icelandic, possessives often come after the noun, especially with family words and very common personal relationships:

• amma mín
• pabbi minn
• vinur minn

So ömmu mína is the normal everyday order.

You can sometimes put the possessive first, but that usually sounds more contrastive or emphatic:

• mín amma can sound more like my grandma, not someone else’s

For ordinary neutral speech, amma mín and its case forms are the pattern learners should expect.

With close family words, Icelandic very often uses the noun without the definite article when a possessive follows.

So forms like these are completely normal:

• amma mín
• mamma mín
• bróðir minn

That is why ömmu mína sounds natural here.

More generally, Icelandic does often use the definite article with possessives in other kinds of nouns, but family terms commonly behave a bit differently. So this is a pattern worth learning as a set phrase type.

Á morgun is a fixed expression meaning tomorrow.

Even though morgun is related to morning, the full phrase á morgun means tomorrow, not on morning in a literal English sense.

It helps to compare:

• í morgun = this morning
• á morgun = tomorrow

So this is best learned as a whole expression rather than translated word by word.

No. In Icelandic, they are treated as separate letters with their own sounds, not just decorated versions of e, o, and a.

In this sentence:

• Ég contains é
• ömmu contains ö
• heimsæki contains æ

That means spelling matters a lot. You should not think of these as optional accent marks. They are part of the normal Icelandic alphabet and can change both pronunciation and meaning.

Yes, absolutely.

You can say:

• Ég heimsæki ömmu mína á morgun.
• Á morgun heimsæki ég ömmu mína.

Both are correct.

But if you put á morgun first, Icelandic usually follows the verb-second pattern. That means the finite verb comes next:

• Á morgun heimsæki ég ömmu mína = correct
• Á morgun ég heimsæki ömmu mína = not the normal Icelandic order

So fronting the time expression is possible, but it changes the word order.

The structure is:

• Ég = subject
• heimsæki = verb
• ömmu mína = direct object
• á morgun = time expression

So the sentence follows a straightforward pattern:

subject + verb + object + time

That makes it a very useful beginner sentence, because even though the word order is simple, it also shows several important Icelandic features at once:

• verb conjugation
• case on the object
• agreement of the possessive
• a common future-time expression