what is the difference algun and alguno/a

Question

what is the difference algun and alguno/a?

Answer 1

It's just a matter of apocopation. Before a masculine, singular noun alguno becomes algún.

Tengo que leer algún libro.

But, if alguno follows the noun, it is not shortened.

Tengo que leer un libro alguno.

the feminine (alguna) and the plurals (algunos, algunas) are not shortened, whether they precede or follow the noun.

The same thing happens with other words like primero (primer) or tercero (tercer). All drop the "o", before a masculine, singular noun.

Spanish apocopation

Notice that some words like cualquiera become cualquier before any noun, masculine or feminine, (mostly singular nouns). After nouns it is cualquiera or cualesquiera. (plural)

Answer 2

thank you so much