Cześć, phobe.lim. Both forms are plural for "kid" or "child" in Polish, but "dzieci" is nominative, accusative and genitive, while "dziećmi" is instrumental. The following sentences exemplify their uses:
Nominative: "Dzieci śpią." = "The children are sleeping." Accusative: "Mam dzieci." = "I have children." Genitive: "Nie mam dzieci." = "I don't have children." Instrumental: "Oni są dziećmi." = "They are children."
I hope it was useful and clear. If you have any doubt, please ask.
If I understand everything right, no. If there is at least one male person in a group, it's oni. One is used either when there is no males or when you don't know what gender are them. So, if there are 'children' and no males are mentioned, you use 'one', if it was told there is at least one boy, it is 'oni'.
@yellkaa, I cannot reply directly.
Normally yes, but that depends on the word that was previously used to described that group. If it was neuter (not male personal) , then one stays, if it was male personal, or names, or boys and girls, it's oni;
also I personally would just not use a pronoun when not necessary, and say "to są dzieci" when referencing kids we see.
This is just what I've learned from reading about Polish grammar recently, but I believe it may be the change from pi to p, which is a soft to hard change. Chłopiec has a fleeting "e", which means it disappears with different forms of the word, and then the consonant pi (or p') hardens to p, so pi/e/c -- p/c-. Due to this change in sound, the masculine hard declensions are used.
This page has examples of words like this: http://grzegorj.w.interiowo.pl/gram/en/przypprz.html#8
Well, I'm not sure about your premise. Is "c" really a soft consonant? I mean, it depends on the context, for instance, in "bogaci", "c" is soft because of "i" and its pronunciation is identical to "ć", as in "pięć". On the other hand, "c" is hard in other contexts, like "chłopcy".
Nevertheless, I think I can give you an answer that doesn't depend on the matter above: "c" is part of the stem already. It's present in its singular form "chłopiec". I couldn't find another Polish word that ends with "c" to compare though.
It is impossible to chłopcy mean "boy" (singular).
Boy is chłopiec/chłopczyk/chłopak (depending on his age and a level of affection).
Boys is usually chłopcy, as chłopaki/chłopczyki is awkward (in Nominative, we use those words with other cases)
Chłopcu is boy in Dative=Locative form of chłopiec.
I typed it wrong but it got accepted. I appreciate if the answer is not always dismissed, in order to heep one encouraged, but I would like it even better when the correct spelling is pointed out in addition. Thus, one could avoid that one would learn the wrong spelling. Some time it shows such a hint. But more often it shows only the translation.