Spelling changes in the Preterite occur because the Preterite vowel endings affect the way some consonants sound.
Remember that in Spanish the G and C have two sounds:
- G in front of the soft vowels "i, e" has a soft English "H" sound: general is pronounced "he-ne-rál".
- G in front of the strong vowels "a, o, u" has a hard "G" sound (as in "gone", "Gap" or "Gumby"): goma "go-mah" .
- C in front of "i, e" has a soft "S" sound.
- C in front of "a, o, u" has a hard "K" sound .
So how does that affect verbs in the Preterite forms?
Well, let's look at Jugar (to Play). It is a U-->UE stem-changing verb. In the present tense, Jugar conjugates as
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
juego | juegas | juega | jugamos | juegan |
The g in Jugar is hard, as in the English word `game'.
When we conjugate Jugar in the Preterite following the regular pattern, it should be:
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
[*jugé] | jugaste | jugó | jugamos | jugaron |
But look at the yo form! Remember the Spanish "g" in front of the soft vowel "e" is pronounced like an English "h".
So *jugé would mean the g had lost the hard g (as in "game") sound, and the last syllable would be pronounced like the English word "hey". To preserve the hard "g" sound, we must add a "u" in front of the "é" to form the correct Yo form:
The "u" makes the "g" hard without changing the " é " vowel sound. The spelling changes result from an effort to reflect the correct pronunciation.
Another example is Buscar. In the present tense, Buscar conjugates as
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
busco | buscas | busca | buscamos | buscan |
The "c" is hard like the letter "k".
When we conjugate Buscar in the Preterite following the regular pattern, it should be:
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
[*buscé] | buscaste | buscó | buscamos | buscaron |
But again, look at the yo form! Remember the Spanish "c" in front of "e" is pronounced like an English "s". So *buscé would mean the "c" had lost the hard "k" sound, and the last syllable would be pronounced like the English word "say". To preserve the hard "k" sound, we must change the "c" to "qu" in front of the "é" to form the correct Yo form:
- Remember that "qu" in Spanish always makes a "k" sound and never an English "kw" (as in "queen") sound.
Another example is Almorzar. In the present tense, Almorzar conjugates as
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
almuerzo | almuerzas | almuerza | almorzamos | almuerzan |
The "Z" has an "S" sound.
When we conjugate Almorzar in the Preterite following the regular pattern (note: no stem-change in the preterite), it should be:
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
[*almorzé] | almorzaste | almorzó | almorzamos | almorzaron |
But again, look at the yo form! Remember the Spanish "Z" occurs only in front of the strong vowels A, O, U.
Think of vocabulary words that end in Z, like the word for pencil, "lápiz". To make it plural we add "es". But the Z isn't paired with the soft vowels E and I. So we must change the Z to C: lápices.
Spanish is very mathematical and reliable: when there is a rule like the Z to C change in front of the soft vowels, Spanish will always enforce this change. So although *almorzé technically would have the same pronunication, we have to honor the rule.
We must change the "Z" to "C" in front of the "é" to form the correct Yo form:
So all verbs ending in -car, -gar, and -zar will make these changes in the Yo form to maintain their original consonant sound and accurately reflect the correct pronunciation.
Another group of verbs with spelling changes are -Er and -IR verbs that have double vowels in their endings like: Leer, Oír, Caer:
Yo | tú | él, ella, usted | nosotros | ellos, ellas, ustedes |
Leer Leí | leíste | leyó | leímos | leyeron |
Oír Oí | oíste | oyó | oímos | oyeron |
Caer Caí | caíste | cayó | caímos | cayeron |
Because the Spanish "i" is weak in the face of a stronger vowel, it requires an accent mark to give it voice (so we can hear it). Otherwise the "i" is overwhelmed by the stronger vowel and becomes a glide.
In the third person singular and plural, the conjugation for Leer would be
*leió and *leieron
The Spanish "i" is the poodle of the Spanish Vowel. It is too weak to be heard between the "o" and the "e". An unaccented "i" between two strong vowels (*oio, *eie or *eio, for example), will change into the semi-consonant (German Shepherd) "y" to facilitate the pronunciation. We saw this occur in the Present Progressive.
All -Er and -Ir verbs whose endings have double vowels will have the Spanish "y" instead of the "i":
Creer, desposeer, desproveer, poseer, proveer, releer, sobreseer, etc.