(Rules of Spanish Accents)
PALABRAS AGUDAS
They have tilde (written accent):
- If they end in vowel, n or s: así , thus, camión , truck, sofás , sofas
- If they have the accent on a weak vowel preceded by a strong one, even though they do not end in vowel, n or s:
Raúl , raíz , root, oíd , listen. - Infinitives ending in -air, -eir and -oir: oír , listen, freír , fry, reír , laugh.
They do not have tilde :
- If they end in any consonant but n or s:
Madrid , prohibir , forbid, temer , fear. - Monosyllabic words, except when there is any confusion in the meaning.
fue , went, dio , gave, vio , saw. - Words ending in -ay, -ey, -oy, -uy.
Uruguay , muy ,very.
PALABRAS LLANAS
They have tilde (written accent):
- If they end in any consonant but n or s: fácil , easy, carácter , personality.
Exceptions: aprecien , they appreciate, confiemos , we trust. - If the accent is on a weak vowel preceded or followed by a strong one: ai, ei, oi, au, eu, ia, io, ua, ue, uo.
Caída , fall, río , river. - If they end in n or s preceded by another consonant.
bíceps , biceps.
They do not have tilde :
- If they end in vowel n or s:
Verbo , verb, Mientras , while. - In the diphthong ui: huir , flee, contribuir , contribute.
Exceptions : lingüística , linguistics , huía , fled .
PALABRAS ESDRÚJULAS Y SOBREESDRÚJULAS
They all have tilde without exception:
Tráfico , traffic, Crítico , critic, Órgano , organ