Italian Grammar: Qualche vs. Alcuni

One topic that confuses many students is the word “some” and the difference between “qualche” and “alcuni/e.”While they both mean “some” to indicate a small quantity, there are some important differences between them.

“Qualche” is always followed by a singular noun and it never changes gender or, they way you’ve heard me say it, it does not match the noun. It always stays in the form “qualche.”  
ie. Hai qualche limone? Do you have any/some lemons?
Avete qualche forchetta in più? Do you have any/some extra forks?
So even if “qualche” translates in the plural in English, in Italian it is always followed by the singular noun.

“Alcuni/e” is always followed by a plural noun and it always has to match the gender of the noun. 
ei. Alcune volte ho la testa fra le nuvole. Some times my head is in the clouds.
Alcuni dei miei amici amano la nutella. Some of my friends love nutella.
I usually prefer to use “qualche” as it is easier since it never changes. However, the more you learn the more you will notice that one usually sounds better than the other one.

Lastly, there is a very important rule to remember:
Both “qualche” and “alcuni/e” must describe a noun that can be quantified. When you say in English “some water,” you cannot use either because you cannot quantify water unless you say “a glass of water”, in which case you would be quantifying the word “glass”. Therefore, in this case, you would you the correct form of “di.”
ei. Vorrei dell’acqua. I would like some water.
Vorrei de vino. I would like to wine.

We hope this helps clarify some confusion and our teachers are always happy to further discuss any topics during the lessons.