What are the accent placement rules in Spanish?

Question

Some people have trouble determining when accent marks (tildes) should be used and where. What are the rules for accent placement in Spanish? How do you determine whether the vowel on the stressed syllable should have an accent mark or not?

Answer 1

There are entonation or accent rules. You only need to use the accent mark (tilde) when a word is pronounced differently to those rules. So here are the general rules:

1. For the words ending with vowel (A, E, I, O, U) or letters S or N: the accent falls on the second last syllable. Example: hermano, casa, campesino. You pronounce these syllables stronger and longer than other syllables. You do not need to add the accent mark.
2. For the words ending with other consonants (not S or N): the accent falls on the last syllable. Example: libertad, reloj, veraz, comenzar, manzanal. You do not need to add the accent mark.
3. Diphthongs: When counting syllables, the weak vowels like I and U do not make a separate syllable when they go with strong vowels like A, E or O. Example: escuela, Mariana, desarraigo

For all words that do not follow above rules, you do need to add an accent mark. For example:

canción, árbol, Martínez

When a weak vowel goes with a strong vowel but it has an own accent, you need to add an accent mark and it counts as a separate syllable. Examples:

Gar-cí-a, grú-a, Ma-rí-a