Lessons in Chemistry

[adamsimonlevine]

To celebrate the end of the school year, here's a 21x21 Sunday stumper that's not for the faint of heart! I decided to create both Regular (non-meta) and Hard (meta) versions, and I'm delighted to share the Hard version here. The meta answer is a seven-word sentence, consisting of Across clues in order, which explains the puzzle's theme. The meta is probably not so challenging for experienced Muggles, but the puzzle itself is definitely on the challenging side. Happy solving! (The Regular version, in which the seven key Across entries are highlighted for you, can be found here.

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[Seattle DB]

Wow, ASL, this looks like a good one. Thank you!

[schmidzy]

Wow, this was cool! Thanks for sharing!

[boharr]

Most impressive. Thank you.

[Al Sisti]

I remember test-solving this some months ago. Loved it then, loved it now.

[MikeyG]

Can't wait to solve this challenge - looks awesome!

[adamsimonlevine]

I realized I never got around to posting any nudges for this puzzle! Here are a few belated ones, along with the meta answer.

Nudge 1: A lot of the clues are pretty strange, don't you think?

Nudge 2: The clues where an Across and Down both start in the same square may be a useful tipoff.

Nudge 3: 31-Across is one of the seven words in the sentence.

Meta answer: ALL CLUES' INITIALS SPELL SYMBOLS FOR ELEMENTS.

[DrTom]

I forgot to post here how much I enjoyed the puzzle. I pretty quickly tumbled to the mechanism then marveled at the cluing. Must have been a labor, but a labor of love.

T

[hoover]

Awwww! I didn't see this one when it first came out. How did I miss it? Amazing! Hope these recent comments attract more solvers!