Epoch when palm trees grew in Alaska / SUN 2-13-22 / Acceptance principle of improv comedy / Dark Lady hitmaker 1974 / Only trisyllabic rainbow color / Country with the most archaeological museums in the world / Scientist whose name is associated with a number / Uncle for whom an annual award is supposedly named

Theme answers:

• UNLIKABLE (23A: *Opposite of endearing) ("K" can be "V")
• UNINHIBITED (24A: *Freely expressive) (second "I" can be "A")
• INTERFACING (46A: *Communicating (with)) ("F" can be "L")
• SHRINKING (49A: *Contracting) ("N" can be "E")
• INVECTIVE (69A: *Harsh language") ("C" can be "N")
• IRRIGATED (87A: *Watered artificially) ("G" can be "T")
• COMPLEMENTS (89A: *Goes well with) (first "E" can be "I")
• ALTERCATION (113A: *Noisy disagreement) ("C" can be "N")
• COMMANDED (116A: *Ordered) ("A" can be "E")

Word of the Day: AVOGADRO's Number (56D: Scientist whose name is associated with a number) —

The Avogadro constant (N_A or L) is the proportionality factor that relates the number of constituent particles (usually molecules, atoms or ions) in a sample with the amount of substance in that sample. Its SI unit is the reciprocal mole, and it is defined exactly as N_A = 6.02214076×10²³ mol⁻¹. It is named after the Italian scientist Amedeo Avogadro. Although this is called Avogadro's constant (or number), he is not the chemist who determined its value. Stanislao Cannizzaroexplained this number four years after Avogadro's death while at the Karlsruhe Congress in 1860.

The numeric value of the Avogadro constant expressed in reciprocal mole, a dimensionless number, is called the Avogadro number, sometimes denoted N or N₀, which is thus the number of particles that are contained in one mole, exactly 6.02214076×10²³.

The value of the Avogadro constant was chosen so that the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the average mass of one molecule of the compound in daltons (universal atomic mass units); one dalton being 1/12 of the mass of one carbon-12 atom, which is approximately the mass of one nucleon (proton or neutron). For example, the average mass of one molecule of water is about 18.0153 daltons, and one mole of water (N molecules) is about 18.0153 grams. Thus, the Avogadro constant N_A is the proportionality factor that relates the molar mass of a substance to the average mass of one molecule, and the Avogadro number is also the approximate number of nucleons in one gram of ordinary matter. (wikipedia)

David is a very good constructor so I really feel like I must be missing something. I found the "VALENTINE" but ... I absolutely needed the "Notes" in order to know that I was even supposed to look for the "VALENTINE," and the "Notes" say explicitly that the "VALENTINE" is a "bonus," so if it's the "bonus," then what ... is the regular ... pay? Like, it's a "bonus" on top of what? How can it be a "bonus"—it really feels like the essence of the gimmick. Otherwise you just have a themeless Sunday. Maybe I would eventually have grasped (from the title) that the answer to the starred clues need a "Change of Heart," but even if I had been able to get it without the notes, that still doesn't change the fact that the "VALENTINE" can't realistically be said to be a "bonus." Further, this seems a rather tepid way to get to "VALENTINE"—asking me merely to imagine a new letter that could be there ... if the puzzle were clued completely differently. I keep looking around for other Valentine-y stuff ... some core idea that I am missing. But I don't see it. I think the theme is just "VALENTINE." Not even a message like "BE MY VALENTINE" or something like that. Just the word. I am a bit at a loss. Doesn't quite seem to have the pop or zing or on-the-money quality that I'd expect from a Sunday holiday puzzle. 

My guess is that many people won't care about the wispy theme because they will be feeling too triumphant at having solved a Sunday puzzle in record or near-record time. There was almost no resistance in this thing. I would say 80% of my struggle came from the single answer PENLIGHT, yipes, absolute stumper, completely unparsable for me (for a bit) (12D: Instrument used in a medical checkup). I also had DONOR (??) instead of HONOR in the adjacent answer (25D: Word with code or card), and had no idea that anyone ever called SRI LANKA the "teardrop of India." I mean, yeah, I guess I see it, now, but yeesh, again, hard to parse. STAPLE was slightly hard because of the "?" clue (54A: What may connect the parts of a school assignment?), and I couldn't make heads/tails of the GENDER clue either (51D: One of three for German nouns, or one of four for hose in Africa's Zande language). But as far as difficulty, that was it—the NE corner. Everything else was dry grass and I was the fire. I kept waiting for a theme to show up (beyond the switch-the-letters theme that I already knew was coming, as a promised "bonus"). But I kept waiting. Still waiting.

Bullets:

• 7D: ___ sandwich (DELI)— really wanted EAT A. But seriously, isn't a DELI sandwich just ... a sandwich. Is it sliced meats? But then, no, it must also be chicken salad, right? Is it just ... I don't know. It's not a term I know. I know that I can get a sandwich at a deli, and I guess pastrami and other cured meats, maybe those seem like DELI sandwiches, but overall the term lacks needed specificity for me.
• 83D: Literally, "revenge" (VENDETTA) — in what language? If you have a VENDETTA, you *want* revenge. You *seek* vengeance. Turns out it's "revenge" in Italian. You coulda said so.
• 105D: 9-5 automaker, once (SAAB)— forgot they existed; wrote FIAT (speaking of Italian)
• 63D: Italian bread that's no longer made (LIRE)— speaking of Italian some more ... what is the difference between LIRA and LIRE!?!? LIRE is the plural. And yet nothing about this clue says plural. So you need the cross for that final vowel.
• 103A: Ending remark that's surprising (KICKER)— well I had UNAPT instead of INAPT, sigh, which meant that my initial "Ending remark that's surprising" was, fittingly: "... SUCKER."

Signed, Rex Parker, King of CrossWorld

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