I need some input from any Italians or Italian language speakers on names that contain these articles. I'm trying to write a mafia short story (just for myself) that has a character that has such name. What I'm puzzled by, is the difference between De, Di and Dei. If I want my character's last name to be Noto, should it be De Noto or Di Noto? And why is there a space between the article and the surname in some names (like Robert De Niro) and not in others (Leonardo DiCaprio)? Thank you very much in advance.

di + il = del
di + lo = dello
di + la = della
di + i = dei
di + gli = degli
di + le = delle

Di is the simple preposition, De is seldom used in Italian, more so Spanish, Portuguese and French.

"de" is what "di" becomes when joining an article.

Quite confusing, it remains "de" even if such joining is actually split, usually when you're quoting the title of a book or something.

Let's say my cousin Mario wrote a book titled "the metaphysics of the female mouse" ("la metafisica del topo femmina").

you could then say

Mario is the author of "the metaphysics of the female mouse"

which should translate as

Mario è l'autore di "la metafisica del topo femmina"

except "di" is close to "la". The two words can't merge and become "della" because that would cross the quote barrier but still it's enough to cause "di" to become "de"

so

Mario è l'autore de "la metafisica del topo femmina"

Di and Da are prepositions and can mean of, from, or by in Italian, depending on context. They do not change when used by themselves, i.e. not followed by a definite article "the". When it comes to proper names, you can figure that they originated to describe the place that the family hails from (Leonardo DA Vinci) or sometimes the person that they descended from, or maybe even the trade they practiced.

There is no DE in modern Italian--in names it may just be a leftover antiquated construction, or perhaps something that was shortened, as in Della or Del, which mean "of the" either feminine or masculine. This is where gender plays a part, and that would be the gender of the word following the preposition.

In any grammar book you can find a chart of all the prepositions and what they become when combined with definite articles in masculine/femminine/singular/plural. This is just another piece of the entire pattern of agreement in number and gender in Italian.

The spacing usually comes down to how the ancestors wrote the name when signing, similar in English as to why we have Smyth and Smith. Leonard DiCaprio technically should be Leonard Di Caprio (As in the above Di Vinci), except one of his ancestors signed it without the space.

Di and Da are prepositions and can mean of, from, or by in Italian, depending on context. They do not change when used by themselves, i.e. not followed by a definite article "the". When it comes to proper names, you can figure that they originated to describe the place that the family hails from (Leonardo DA Vinci) or sometimes the person that they descended from, or maybe even the trade they practiced.
There is no DE in modern Italian--in names it may just be a leftover antiquated construction, or perhaps something that was shortened, as in Della or Del, which mean "of the" either feminine or masculine. This is where gender plays a part, and that would be the gender of the word following the preposition. In any grammar book you can find a chart of all the prepositions and what they become when combined with definite articles in masculine/femminine/singular/plural. This is just another piece of the entire pattern of agreement in number and gender in Italian.

The Surname Caprio is a name for a Goat, having derived its origin from the Italian capra. Niro is a southern variant of Nero, meaning black.

Thank you very much Raoul.

:D

interesting stuff. i actually read it.