The rules for the placement of written accent marks in Spanish are simple. If you see a word written in Spanish and you know these rules, you should be able to say the word and stress the correct syllable. If you are writing, however, you must be able to pronounce the word before you will be able to apply the rules and write the word properly. Here are three rules and an additional comment:
1. Spanish words ending in a vowel, n, or s
If the word ends in a vowel, the letter “n,” or the letter “s,” the stress is on the next-to-the-last syllable.
ha-BLA-do ar-gu-MEN-tos LI-bra o-RI-gen ME-sa
2. Spanish words ending in a consonant other than n or s
If the word ends in a consonant other than the letter “n” or the letter “s,” the stress is on the last syllable.
to-TAL com-ple-TAR lo-CUAZ sim-pli-ci-DAD
3. Exceptions to Rules 1 and 2
If the stress is on any syllable other than those covered in Rules 1 and 2, then an accent is written on that syllable. In order to write the word correctly, you must know its proper pronunciation. If you see it already correctly written, however, pronouncing it should be easy.
Accents used to distinguish one Spanish word from another
Accents are used, as well, to distinguish words that have the same form but different meanings. The presence or absence of the accent mark does not alter the pronunciation of the word.
si (if) vs sí (yes) mi (my) vs mí (me) de (of) vs dé (give)
An observant listener can note a difference in the ways these words are stressed with respect to the rest of the sentence. This is especially true for words like “que” vs “qué,” “como” vs “cómo,” etc.