There are three basic rules to put tilde (´) over words in Spanish . These rules depends on accentuation (stress) in different syllables (phonetic division). The syllable most strength of intonation (accent) is named stressed syllables and the rest are no stressed syllables.
According to the accentuation, the words are:
√ Oxytone The strength of intonation (accent) is on the last syllable.
(Example: ba- lón (“ball”); Ma- drid, pa- red (“wall”)).
These type of words only have tilde if end in -n, -s or vowel.
A-cep-tar (to accept)
The stress in on the penultimate syllable or in the second syllable starting from the end. (Examples: Pla-ya (“beach”), va-ya (“go to”), cam-pa-na (“bell”). The Spanish is a paroxytone languages, that is, in the majority of cases the stress is this position.
Paroxytones words have tilde if these no end in -n, -s or vowel.
Ejemplos: Án-gel (“Angel”)
√ Proparoxytone and preantepenultimate syllable
The stress is on ante-penultimate syllable or ahead of this; that is, from third syllable starting from the end (Example: pá-ja-ro (“bird”) ).
These words always has tilde.
Examples: Me-cá-ni–co (“Mechanic”)
Cán-ta–lo (“Sing it”)
By Veronica Rodriguez , who is graduate in Spanish Language and Hispanic literatures by the University of Las Palmas de Gran Canaria, for Practica Español
(Text translated by Sandra Municio)