wurtzite - 2026 ACF Regionals

Question

This crystal structure is the most stable configuration for cadmium selenide nanoparticles used to assemble quantum dots. For 10 points each:

[10h] Name this structure composed of tetragonal unit cells arranged in a hexagonal close-packing configuration. Sphalerite can be transformed into this structure by heating zinc sulfide crystals at over 1,000 degrees Celsius.

ANSWER: wurtzite [accept cadmoselite or greenockite or máitrete; prompt on w]

[10m] Gallium and this species form wurtzite crystals used in blue LEDs, whose development won the 2014 Nobel Prize in Physics. Hexagonal crystals of boron and this species form ferroelectric “white graphene” monolayers.

ANSWER: nitride [or N3−; accept gallium nitride or GaN; accept boron nitride or BN; reject “nitrogen” or “nitrate” or “nitrite”]

[10e] Analogous to diamond, boron nitride in its sphalerite form has this crystal geometry system instead, whose face-centered type has an atomic packing factor about 0.06 larger than its body-centered type.

ANSWER: cubic [accept cube; accept face-centered cubic or fcc; accept body-centered cubic or bcc; accept cubic closed-packed or ccp]

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Summary


California (North)	Main Site	Y	3	20.00	100%	33%	67%
California (South)	Main Site	Y	4	10.00	75%	25%	0%
Canada	Main Site	Y	10	9.00	70%	10%	10%
Florida	Main Site	Y	3	6.67	67%	0%	0%
Great Lakes	Main Site	Y	5	14.00	100%	40%	0%
Lower Mid-Atlantic	Main Site	Y	9	8.89	78%	11%	0%
Midwest	Main Site	Y	8	10.00	88%	13%	0%
Northeast	Main Site	Y	6	11.67	83%	33%	0%
Overflow	Main Site	Y	4	7.50	75%	0%	0%
South Central	Main Site	Y	2	5.00	50%	0%	0%
Southeast	Main Site	Y	7	10.00	86%	14%	0%
UK	Main Site	Y	12	6.67	58%	8%	0%
Upper Mid-Atlantic	Main Site	Y	8	10.00	88%	13%	0%
Upstate NY	Main Site	Y	4	10.00	75%	0%	25%

Data


Stanford A	Berkeley A	0	0	10	10
Berkeley B	Berkeley D	10	10	10	30
Stanford B	Berkeley C	10	0	10	20
UC Irvine	UC Santa Barbara	0	0	0	0
UCLA A	Arizona State	0	10	10	20
UCSD A	UCLA B	0	0	10	10
UCSD B	UCSD C	0	0	10	10
Queen's	Simon Fraser	0	0	10	10
Toronto B	Carleton University	0	10	10	20
Waterloo B	Guelph	0	0	10	10
McGill B	Western C	0	0	0	0
Brock	McMaster B	0	0	0	0
Ottawa	Waterloo A	0	0	10	10
Toronto Metropolitan	Western B	0	0	0	0
Toronto C	Toronto D	0	0	10	10
Florida B	Central Florida A	0	0	0	0
Central Florida B	Florida A	0	0	10	10
Florida C	Central Florida C	0	0	10	10
McMaster A	Toronto F	10	0	10	20
Michigan A	Michigan B	0	0	10	10
Ohio State A	Michigan C	0	0	10	10
CWRU A	Ohio State B	0	10	10	20
CWRU B	Ohio State C	0	0	10	10
Pittsburgh	Michigan State	0	10	10	20
UBC A	Western A	0	0	10	10
Duke	NC State A	0	0	10	10
Virginia Tech B	James Madison A	0	0	10	10
VCU	James Madison B	0	0	0	0
Liberty A	Liberty C	0	0	10	10
Virginia	NC State B	0	10	10	20
William and Mary	North Carolina A	0	0	10	10
South Carolina A	Wake Forest	0	0	10	10
North Carolina C	South Carolina B	0	0	10	10
Liberty B	Virginia Tech A	0	0	0	0
Indiana A	Purdue B	0	10	10	20
Illinois B	Illinois A	0	0	10	10
Northwestern B	Notre Dame A	0	0	10	10
Notre Dame B	Chicago D	0	0	0	0
Purdue A	Indiana C	0	0	10	10
Chicago A	Indiana B	0	0	10	10
Harvard A	Brandeis B	0	10	10	20
Dartmouth A	Southern Connecticut State	0	0	10	10
Harvard B	Bowdoin A	0	0	10	10
Yale	Bowdoin B	0	0	10	10
Brandeis A	Dartmouth B	0	0	0	0
MIT	Brown	0	10	10	20
Chicago E	Northwestern C	0	0	10	10
Missouri A	Minnesota A	0	0	10	10
Georgia Tech A	Washington B	0	0	10	10
Texas A&M A	Texas B	0	0	0	0
Murray State A	Texas A	0	0	10	10
Northwestern D	Illinois C	0	0	10	10
Claremont	Washington A	0	0	10	10
Missouri B	Iowa State	0	0	0	0
Bruin	Alabama A	0	0	10	10
Louisville B	Alabama B	0	10	10	20
Georgia Tech C	Kentucky	0	0	10	10
Louisville A	Mississipi State	0	0	10	10
Georgia Tech D	Tennessee B	0	0	10	10
Vanderbilt B	Sewanee	0	0	0	0
WashU B	Georgia Tech B	0	0	10	10
Imperial A	Bristol	0	10	10	20
Birmingham	Imperial B	0	0	0	0
Edinburgh A	Cambridge A	0	0	10	10
Warwick B	Cardiff	0	0	0	0
UCL	Edinburgh B	0	0	10	10
Southampton A	Montpellier	0	0	10	10
Oxford A	Cambridge B	0	0	10	10
Cambridge C	Oxford B	0	0	0	0
Oxford C	Southampton B	0	0	10	10
Imperial C	City St. George's	0	0	0	0
LSE	Durham	0	0	0	0
Columbia A	Georgetown	0	0	10	10
John Jay	Columbia C	0	0	10	10
Johns Hopkins A	Maryland B	0	0	10	10
Vassar	Johns Hopkins B	0	0	0	0
NYU A	Rutgers B	0	10	10	20
NYU B	Maryland C	0	0	10	10
Columbia B	NYU C	0	0	10	10
Rutgers A	Swarthmore	0	0	10	10
Binghamton A	Binghamton B	0	0	0	0
Cornell A	Cornell C	0	0	10	10
Penn State	RIT	10	0	10	20
Cornell B	Rochester	0	0	10	10
Manchester	Warwick A	0	0	10	10