Learn Hardcore German: Ich habe schon einen ganzen Stapel Vokabelkarten, aber es sind nie genügend für alle neuen Ausdrücke. - I already have a whole pile of vocabulary cards, but there are never enough for all the new expressions.

Stapel = masculine ( der Stapel = the stack/pile)
In the sentence, einen ganzen Stapel Vokabelkarten is the direct object of haben:
- Ich habe was? – einen ganzen Stapel Vokabelkarten → accusative.

Masculine ein-words in the accusative:

nominative: ein ganzer Stapel (subject)
accusative: einen ganzen Stapel (object)

So einen and ganzen both show accusative masculine.

What is the function of schon in Ich habe schon einen ganzen Stapel …? Could I leave it out?

Here schon means already and adds a nuance of “by now / at this point”.

Ich habe einen ganzen Stapel Vokabelkarten.
→ I have a whole stack of vocabulary cards. (neutral statement)
Ich habe schon einen ganzen Stapel Vokabelkarten.
→ I already have a whole stack of vocabulary cards. (emphasizes “already” and often a sense of “and it’s still not enough / and it’s surprising / and it’s a lot”)

You can leave it out grammatically, but you lose that nuance. The contrast with the second part (aber es sind nie genügend …) becomes weaker if you omit schon.

Position: in main clauses, schon is typically placed in the “middle field,” after the subject and verb:

Ich (subject) habe (verb) schon (middle field) einen ganzen Stapel Vokabelkarten (rest of the clause).

Why is it es sind nie genügend and not sie sind nie genügend?

Here es is a dummy subject, similar to English “there” in “there are never enough…”.

es sind nie genügend … ≈ there are never enough …

We are not literally talking about “it”; es just fills the subject slot so the verb can be conjugated. The real idea is existential: “the amount of cards that exists is never enough.”

Using sie would refer back to a specific feminine/plural noun mentioned right before as a grammatical subject, e.g.:

Die Vokabelkarten sind nie genügend für alle neuen Ausdrücke.
→ Sie sind nie genügend … (here sie = die Vokabelkarten)

But in aber es sind nie genügend für alle neuen Ausdrücke, the structure is:

es (dummy subject)
sind (verb)
nie genügend (predicate: “never enough (of them)”)

So es is the correct choice for this impersonal “there are …” construction.

What does genügend do here? Why is there no noun after it, like genügend Karten?

In es sind nie genügend für alle neuen Ausdrücke, genügend is used by itself and means “enough (of them)”. The noun (Vokabelkarten) is omitted because it’s clear from context.

You could say:

… aber es sind nie genügend Vokabelkarten für alle neuen Ausdrücke.

But in everyday German it’s very natural to drop the noun once it’s understood:

Ich habe schon einen ganzen Stapel Vokabelkarten, aber es sind nie genügend (Vokabelkarten) für alle neuen Ausdrücke.

Here genügend functions like an adverb/adjectival predicate: “enough (ones)” / “a sufficient number (of them)”.

What is the difference between genug and genügend? Could I say es sind nie genug instead?

Yes, you could absolutely say:

… aber es sind nie genug für alle neuen Ausdrücke.

Both genug and genügend mean “enough, sufficient.”

Nuance:

genug
- Very common, neutral, everyday.
- Works in almost all contexts.
genügend
- Slightly more formal or bookish, depending on context.
- Also used as a grade in schools: genügend = “sufficient / pass”.

In this sentence, both sound fine. Genug would sound a bit more colloquial; genügend sounds a touch more formal or “proper,” but not strange.

Why is it für alle neuen Ausdrücke and not some other case? What case is that?

The phrase für alle neuen Ausdrücke is in the accusative plural.

Reason: the preposition für always takes the accusative:

für wen? / für was? → accusative

Breakdown:

Ausdruck (singular) → Ausdrücke (plural)
alle – determiner (all)
neu – adjective

Accusative plural with a “definite-like” determiner (alle behaves like die):

für alle neuen Ausdrücke

Pattern:

nominative plural: alle neuen Ausdrücke (subject)
accusative plural: alle neuen Ausdrücke (object / after für)

So here alle neuen Ausdrücke is accusative plural, governed by für.

What exactly does ganzen mean in einen ganzen Stapel? Is it just “whole”, or does it add some emphasis?

Literally, ganzen is the accusative masculine form of ganz = whole, entire:

ein ganzer Stapel – a whole stack
einen ganzen Stapel – (accusative) a whole stack

In this context, ganzen also adds emphasis, similar to English:

a whole stack of vocabulary cards (implies “and that’s quite a lot”)

So the phrase suggests:

not just a few cards, but an entire/large stack, and yet it’s still not enough.

It’s both literal (not a half-stack) and intensifying (“a lot”).

Why is the verb order aber es sind nie genügend … and not aber es nie sind genügend …?

In a main clause, German normally keeps the finite verb in second position (the V2 rule).

Clause 1:

Ich (1st field)
habe (2nd = verb)
schon einen ganzen Stapel Vokabelkarten (rest)

Clause 2 after aber:

aber – coordinating conjunction (does not take the verb to the end; it just links two main clauses)
es (1st field in the new clause)
sind (2nd = verb)
nie genügend für alle neuen Ausdrücke (rest)

So the correct order is:

aber es sind nie genügend …

Putting nie before sind (→ aber es nie sind genügend …) would break the V2 rule for main clauses and sounds ungrammatical.

Could I drop es and say … aber sind nie genügend für alle neuen Ausdrücke?

No, you can’t drop es here. German normally needs an explicit subject, even when it’s just a dummy pronoun.

You must have:

aber es sind nie genügend … (with es)

Compare with English:

✅ There are never enough for all the new expressions.
❌ Are never enough for all the new expressions.

Just like English needs “there”, German needs es in this existential structure.

What exactly are Vokabelkarten? Why plural here, and how is the word formed?

Vokabelkarten is the plural of die Vokabelkarte:

die Vokabel – vocabulary item / word
die Karte – card
die Vokabelkarte – vocabulary card (like a flashcard)
plural: die Vokabelkarten

In the sentence, the speaker has many of them, so the plural is natural:

einen ganzen Stapel Vokabelkarten → a whole stack of vocabulary cards.

That is why later the implicit reference in es sind nie genügend (Vokabelkarten) is also plural in meaning: never enough cards.