# Should one pronounce “periodic” the same in “periodic acid” and “periodic table”?

In “periodic table”, the adjective is related to the noun period, and comes from Ancient Greek περίοδος through French périodique. In “periodic acid”, it is formed from the prefix per- and iodic (like peroxide and permanganate).

Wiktionary lists their respective UK pronunciations of as /pɪə(ɹ).iˈɒdɪk/ and /ˌpɜːraɪˈɒdɪk/, markedly different: pɪə (as in piece) vs. pɜː (as in perfume); then i (as in it) vs. aɪ (as in eye).

However, is that distinction really made in practice? Would a native US/UK/Aussie speaker make the difference when talking in the lab?

• It only just occured to me that those words are written the same :) – Mithoron Jul 31 '15 at 13:39
• I actually call periodic acid period acid just for fun ;D – Jan Nov 8 '17 at 12:52
• Do you "read" books? I have "read" a few. – Oscar Lanzi Nov 8 '17 at 13:29

I am an Australian English speaker and yes, this distinction is made in practice.

Possibly the only reasonable opportunity to use the pɪə pronunciation in the name of a compound is in the case of the entertaining molecule periodane, which is actually named after the periodic table. This molecule (and later a number of different plausible isomers) was identified computationally by a methodology called 'mindless chemistry' which optimises randomly generated molecular graphs. Periodane is a stable configuration of each atom on the second row of the periodic table, with the exception of neon (although some people are working on that).

I'm not a professional chemist, just a student, but here are some observations from which I can speculate:

Note-- in this post,

/ˌpɜːraɪˈɒdɪk/==per-iodic

/pɪə(ɹ).iˈɒdɪk/==peer-iodic

(since IPA is annoying to read)

Remember, it's written as "per-iodic" acid many times. Which means it must be pronounced as "per-iodic" by whoever who reads/writes those texts. So we have some evidence showing the use of "per-iodic" as a pronunciation. I don't see any such evidence for "peer-iodic", though one of my teachers used it. I myself initially used "peer-iodic", but once I realized what the acid actually was, I switched to "per-iodic".

It is supposed to be pronounced as per-iodic acid schiff but there are many people who dont know that it contains iodine and call it peeriodic acid.