The word "joven" is grave, it is stressed on the second last syllable, it ends in "n", so the stress is not written, but "jóvenes", the plural adds one more syllable, so this is not a grave word anymore (even though it continues to be stressed on the same root syllable), it is an esdrújula word, which means that the stress is written regarless the ending of the word. "Canción" is an aguda word, it is stressed on the last syllable, it ends in "n" so the stress is written. "Canciones", the plural added one more syllable, so this is not an aguda word anymore, it is a grave word (though, again, it continues to be pronounced stressing the same root syllable). Since it ends in "s", the stress is not written. I hope you find this explanation useful. If you happen to have more questions, please, let me know. Cheers.

That is because the accent is placed where it is gramatically correct instead of where it was in it singular form: If a word is "aguda" (the last syllable is stressed), the word is accented if it end in n, s, or a vowel (just like "canción"). If a word is "grave" (the second to last syllable is stressed), the word is accented if it does not end in n, s, or a vowel (such as "lápiz", both "joven" and "canciones" are graves but the end in n and s, respectively). Any other word will always get an accent, such as "jóvenes". If something wasn't clear enough, please let me know!

Agudas (words stressed on the last syllable), the stress is written only when the word ends in a vowel or letters "s" or "n". For example: Mansión (man -sión)= two syllables, the last syllable is stressed and the word ends in "n"... The stress is written. Café (ca-fé) = two syllables, the last syllable is strssed and the word ends in vowel... The stress is written. Japonés (ja-po-nés) = three syllables, the last syllable is stressed and the word ends in "s"... The stress is written. Utilizar (u-ti.li-zar) = four syllables, the last syllable is stressed but the word ends in "r" (not vowel, s or n)... The stress is not written... But it continues to be pronounced with the stress on the last syllable. Integridad (in-te-gri-dad) Same. Graves (words are stressed on the second last syllable). This time, the stress will be written when the word ends in letters others than vowels, s and n. If the grave word ends in vowel, n or s, then the stress will not be written. Martes (mar-tes)= two syllables, the word is stressed on the second last syllable and the word end in "s"... The stress is not written. Problema (pro-ble-ma)= three syllables, the word is stressed on the second last syllable and it ends in vowel... The stress is not written. Volumen (vo-lu-men)= three syllables, the word is stressed on the second last syllable and the word ends in "n"... The stress is not written. Árbol (ár-bol)= two syllables, the word is stressed in the second last syllable and ends in "l" (not vowel, n or s)... The stress is written. To be continued...

Hey Ashley. The words do not lose their accent, they lose their "written accent", they continue to be pronounced stressing the same syllable though. The change has to do with the stress system in Spanish. There are four types, id est "agudas", "graves", "esdrújulas", "sobreesdrújulas". Every single one tells you where the word is stressed, weather the stress is written or not. So, think of a word of four syllables. (Fourth Last Syllable) + (Third Last Syllable) + (Second Last Syllable) + (Last Syllable). Every single one of this syllables may be stressed, so if we say that a word is "aguda" it means that it is stressed on the last syllable, if we say that a word is "grave" it means that it is stressed on the second last syllable... "Esdrujulas" on the third last syllable and "sobreesdrújulas" on the fourth last syllable. Now... In the case of esdrújulas and sobre-esdrújulas, the stress is always written. For example: Héroe (hé-ro-e) = three syllables, stressed in the third last syllable, the stress must be written. Órdenes (ór-de-nes) Same. Llévatelo (llé-va-te-lo) = four syllables, it is stressed on the fouth last syllable, stress must be written. Ágilmente (á-gil-men-te) = same. Well, with agudas and graves the story is a little different, though the rules are consistent. To be continued...