Spanish conjugation explanation
Diphthongization
<p>In certain forms of certain Spanish verbs, the vowel <span style="font-style: italic;">-e-</span>, <span style="font-style: italic;">-i-</span>, <span style="font-style: italic;">-o-</span> or <span style="font-style: italic;">-u-</span> turns into a diphthong (=double vowel: <span style="font-style: italic;">-ie-</span> or <span style="font-style: italic;">-ue-</span>). This vowel change is called <strong>diphthongization</strong>.</p>
<p>The identity of diphthongizing verbs must be learned individually (you can find a list of common examples further below). However, if we understand the logic behind it, we can quickly figure out which forms of a diphthongizing verb are affected.</p>
<p>Let's start by summarizing the different types of diphthongization:</p>
<div class="table_container">
<div class="three_column_table">
<div><strong>Vowel change</strong></div>
<div><strong>Verb</strong></div>
<div><strong>Verb form</strong></div>
<div><strong>e → ie</strong></div>
<div>pensar</div>
<div>yo p<strong>ie</strong>nso<div style="font-style: italic;">(I think)</div></div>
<div><strong>i → ie</strong></div>
<div>adquirir</div>
<div>yo adqu<strong>ie</strong>ro<div style="font-style: italic;">(I acquire)</div></div>
<div><strong>o → ue</strong></div>
<div>dormir</div>
<div>yo d<strong>ue</strong>rmo<div style="font-style: italic;">(I sleep)</div></div>
<div><strong>u → ue</strong></div>
<div>jugar</div>
<div>yo j<strong>ue</strong>go<div style="font-style: italic;">(I play)</div></div>
</div>
</div>
<p>The vowel change can only occur in the stem of the verb (for example, we get the stem of the verb <span style="font-style: italic;">pensar</span> by removing the <span style="font-style: italic; white-space: nowrap;">-ar</span> ending → <span style="font-style: italic;">pens</span>). More specifically, it occurs when <strong>the stressed syllable is in the stem</strong>.</p>
<div class="conjugation_explanation_title">Stressed syllables</div>
<p>A syllable is always stressed if its vowel has an acute accent (´) over it. Consequently, verb forms like <span style="font-style: italic;">él pensó (he thought)</span> will keep their stem unchanged (because the stress is outside them stem).</p>
<p>For all other words, the stressed syllable is determined by the last letter of the word (note: when a weak vowel (<span style="font-style: italic;">i</span> or <span style="font-style: italic;">u</span>) combines with another vowel, they form one sound within the same syllable):</p>
<ul>
<li>If the word ends in a <strong>vowel, <span style="font-style: italic;">-s</span> or <span style="font-style: italic;">-n</span></strong>, the stress is on the <strong>second to last syllable</strong>.</li>
<li>If the word ends in a <strong>consonant other than <span style="font-style: italic;">-s</span> and <span style="font-style: italic;">-n</span></strong>, the stress is on the <strong>last syllable</strong>.</li>
</ul>
<p>According to these rules, the only verb forms that are stressed in their stems are the <strong>singular forms</strong> and the <strong>third-person plural form</strong> of the <strong>present indicative</strong>, the <strong>present subjunctive</strong> and the <strong>imperative</strong>. They can be remembered by the distinctive L-shape that they form in their conjugation table:</p>
<div class="study_conjugations_tense_container">
<a class="study_conjugations_tense_label box_label tense_box no_dark_mode " href="/study/tenseGuideForTense/14/" target="_blank" title="Open tense guide">Presente</a>
<div class="study_conjugations_conjugation conjugations_table two_columns">
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
yo
</span><span class="irregular_conjugation" title="irregular conjugation">pienso<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
tú
</span><span class="irregular_conjugation" title="irregular conjugation">piensas<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
él
</span><span class="irregular_conjugation" title="irregular conjugation">piensa<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
nosotros
</span>pensamos
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
vosotros
</span>pensáis
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
ellos
</span><span class="irregular_conjugation" title="irregular conjugation">piensan<span class="irregularity_circle">●</span></span></span>
</div>
</div>
</div>
</div>
<div class="study_conjugations_tense_container">
<a class="study_conjugations_tense_label box_label tense_box no_dark_mode " href="/study/tenseGuideForTense/19/" target="_blank" title="Open tense guide">Presente subjuntivo</a>
<div class="study_conjugations_conjugation conjugations_table two_columns">
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
yo
</span><span class="irregular_conjugation" title="irregular conjugation">piense<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
tú
</span><span class="irregular_conjugation" title="irregular conjugation">pienses<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
él
</span><span class="irregular_conjugation" title="irregular conjugation">piense<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
nosotros
</span>pensemos
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
vosotros
</span>penséis
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
ellos
</span><span class="irregular_conjugation" title="irregular conjugation">piensen<span class="irregularity_circle">●</span></span></span>
</div>
</div>
</div>
</div>
<div class="study_conjugations_tense_container">
<a class="study_conjugations_tense_label box_label tense_box no_dark_mode " href="/study/tenseGuideForTense/22/" target="_blank" title="Open tense guide">Imperativo afirmativo</a>
<div class="study_conjugations_conjugation conjugations_table two_columns">
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span class="study_conjugations_pronoun conjugation_pronoun">---</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
(tú)
</span><span class="irregular_conjugation" title="irregular conjugation">piensa<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
(usted)
</span><span class="irregular_conjugation" title="irregular conjugation">piense<span class="irregularity_circle">●</span></span></span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
(nosotros)
</span>pensemos
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
(vosotros)
</span>pensad
</span>
</div>
</div>
<div class="study_conjugations_forms conjugation_forms highlighted_conjugation">
<div class="conjugation_form">
<span><span class="study_conjugations_pronoun conjugation_pronoun">
(ustedes)
</span><span class="irregular_conjugation" title="irregular conjugation">piensen<span class="irregularity_circle">●</span></span></span>
</div>
</div>
</div>
</div>
<p>Make sure that you understand why each of these verb forms are affected. You should also take your time to study the conjugation tables of <a class="clickable" href="/study/conjugations/esp/pensar/" target="_blank">pensar</a>, <a class="clickable" href="/study/conjugations/esp/adquirir/" target="_blank">adquirir</a>, <a class="clickable" href="/study/conjugations/esp/dormir/" target="_blank">dormir</a> and <a class="clickable" href="/study/conjugations/esp/jugar/" target="_blank">jugar</a> to understand why none of the other verb forms are (pay attention to the stressed syllable).</p>
<div class="conjugation_explanation_title">Common diphthongizing verbs</div>
<p>As we said before, the identity of diphthongizing verbs has to be learned individually. We should mention the most common ones for each category:</p>
<ul>
<li><strong>e → ie:</strong> <span style="font-style: italic;">querer, sentir, pensar, comenzar, perder, entender, empezar, convertir, cerrar, sentar, referir, despertar, mentir, divertir, preferir, sugerir</span>, etc.</li>
<li><strong>i → ie:</strong> <span style="font-style: italic;">adquirir, inquirir</span></li>
<li><strong>o → ue:</strong> <span style="font-style: italic;">poder, encontrar, volver, contar, morir, recordar, probar, mostrar, dormir, volar, sonar, mover, soñar</span>, etc.</li>
<li><strong>u → ue:</strong> <span style="font-style: italic;">jugar</span></li>
</ul>
<p>Common <strong>non-diphthongizing verbs</strong> with <span style="font-style: italic;">-e-</span> or <span style="font-style: italic;">-o-</span> in their stems are: <span style="font-style: italic;">deber, creer, llegar, dejar, llevar, esperar, conocer, tomar, poner, parecer, quedar</span>, etc.</p>
<div class="conjugation_explanation_title">Special cases</div>
<ul>
<li>When the first letter of the verb form is replaced by <span style="font-style: italic;">ie-</span>, it becomes <span style="font-style: italic;">ye-</span>:
<p style="text-align: center;"><span style="font-style: italic;">errar</span> → <span style="font-style: italic;">yo <strong>ye</strong>rro</span></p>
<li>When the first letter of the verb form is replaced by <span style="font-style: italic;">ue-</span>, it becomes <span style="font-style: italic;">hue-</span>:
<p style="text-align: center;"><span style="font-style: italic;">oler</span> → <span style="font-style: italic;">yo <strong>hue</strong>lo</span></p>
<li>When the vowel after <span style="font-style: italic;">g</span> is replaced by <span style="font-style: italic; white-space: nowrap;">-ue-</span>, it becomes <span style="font-style: italic;">-üe-</span>:
<p style="text-align: center;"><span style="font-style: italic;">avergonzarse</span> → <span style="font-style: italic;">yo me averg<strong>üe</strong>nzo</span></p>
</ul>