What are some exceptions for identifying masculine and feminine nouns?

Question

I don't like reading and I got a lot of questions like this.

I did search "definite article" but have yet found a article that address this.

Let me give an example so those confused by my wording may know what I am talking about:

El alma, & las almas

I am not sure what is the reason for this though. It may be either that "la alma" sounds weird or that "alma" begins with a vowel.???

But yea, another example is words with specific endings, like "-cion"

Edit. There are many more examples like the ending "-dad".

Answer 1

Feminine words that use masculine articles are explained thoroughly in paragraph two of this articles from the DPD. It also explains the exceptions to the general rule (feminine nouns starting in a stressed a- use the masculine article). But, in any case, words like alma don't change their gender; alma is feminine, even if it uses a masculine article:

Juan rezó por el alma santa de su madre.
Juan rezó por la santa alma de su madre.

As for the rules to deduce the gender of a noun, there are some partial rules, but most of them have exceptions and, in any case, they don't cover all cases.

Answer 2

You use the masculine articles "el" and "un" before nouns that start with a stressed "a" sound (source: Diccionario Panhispánico de Dudas), independently of their true gender, which can be revealed by (1) changing the noun to plural or by (2) adding an adjective.

For example, ábaco is masculine, but hacha (which also starts with an "a" sound because the h is silent) is feminine:

Un ábaco, el ábaco

1) Unos ábacos, los ábacos

2) Un ábaco viejo

Un hacha, el hacha

1) Unas hachas, las hachas

2) Un hacha afilada

Note that the initial "a" sound has to be stressed. Otherwise, you have to use feminine articles before feminine nouns, even in singular.

Una amiga, la amiga

An exception to this rule is "arte", which is masculine in singular and feminine in plural. "Un arte milenario", but "las bellas artes".

"A", "hache" and "alfa" are exceptions as well, but because they are feminine, start with a stressed "a" sound and use the usual feminine articles "una" and "la".