Maíz vs. Lápiz vs. Feliz
Does maíz have an accent because it is a "hiato"?
That is the only thing that will make sense for me because it doesn't follow the rules found in the words lápiz and feliz.
2 Answers
Maíz has an accent to stress the "i" sound. Mah-EES. Without the accent it would sound like "mice." Whenever the weak vowel in a dipthong is stressed it gets the "tilde."
Consider "historia" and biología. Historia sounds like ees-TOH-ria. Whereas biololgía sounds like "Byo-lo-HEE-ah.
Here's a link to an article I wrote on accent marks. I have also bumped it up to the first page of questions and answers.
Link to accent marks
¡Sí, señor!