All AP Chemistry Resources
Example Questions
Example Question #611 : Ap Chemistry
How many yellow spheres and green spheres are there per unit cell shown?
4 yellow, 1 green
2 yellow, 1 green
8 yellow, 1 green
None of the above
1 yellow, 1 green
1 yellow, 1 green
For a unit cell, the corners count as 1/8 of a sphere and atoms completely within the unit cell count as 1. This gives us 1 yellow and 1 green sphere in the unit cell shown above.
Example Question #1 : Structure Of Ionic Solids
Based upon the above image, what type of packing is this?
Cubic close packing (ccp)
Simple cubic packing (scp)
Hexagonal close packing (hcp)
Body centered packing (bcp)
Tetragonal close packing (tcp)
Cubic close packing (ccp)
The figure above represents ABCABC packing which is cubic close packing.
Example Question #2 : Structure Of Ionic Solids
Based upon the above image, what type of packing is this?
Simple cubic packing (scp)
Tetragonal close packing (tcp)
Cubic close packing (ccp)
Hexagonal close packing (hcp)
Body centered packing (bcp)
Hexagonal close packing (hcp)
The figure above represents ABABA packing which is hexagonal close packing.
Example Question #3 : Structure Of Ionic Solids
Zinc Sulfide can be described as a cubic close packed arrangement of Zn with sulfur occupying one-half of the tetrahedral holes. Based upon that description and the figure above, what is the formula for zinc sulfide?
ZnS
Zn2S
ZnS2
Zn12S4
Zn3S
ZnS
The figure above has 8 Zn atoms on the corners (counting as 1/8) and 6 Zn atoms on the faces (counting as ½). This gives 4 Zn atoms in the unit cell. The Sulfur atoms are completely within the unit cell and count as 1 each for a total of 4 S atoms. This gives the formula Zn4S4 which reduces down to ZnS.
Example Question #4 : Structure Of Ionic Solids
What are the names of the alloy types shown in the figure above:
A = Interstitial; B = Pure metal; C = Substitutional
None of the above
A = Pure Metal; B = Interstitial; C = Substitutional
A = Pure Meta; B = Substitutional; C = Interstitial
A = Substitutional; B = Interstitial; C = Pure Metal
A = Pure Meta; B = Substitutional; C = Interstitial
An interstitial alloy has a smaller atom inserted into the unit cell, a substitutional alloy has another atom substitute for the main element, and a pure metal is only composed of a single atom type.
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