AP Chemistry : Structure of Ionic Solids

Study concepts, example questions & explanations for AP Chemistry

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Example Questions

Example Question #1 : Structure Of Ionic Solids

 01

How many yellow spheres and green spheres are there per unit cell shown?

Possible Answers:

2 yellow, 1 green

1 yellow, 1 green

4 yellow, 1 green

None of the above

8 yellow, 1 green

Correct answer:

1 yellow, 1 green

Explanation:

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 #71 : Compounds And Molecules

02

Based upon the above image, what type of packing is this?

Possible Answers:

Body centered packing (bcp)

Hexagonal close packing (hcp)

Cubic close packing (ccp)

Tetragonal close packing (tcp)

Simple cubic packing (scp)

Correct answer:

Cubic close packing (ccp)

Explanation:

The figure above represents ABCABC packing which is cubic close packing.

Example Question #611 : Ap Chemistry

03

Based upon the above image, what type of packing is this?

Possible Answers:

Simple cubic packing (scp)

Body centered packing (bcp)

Hexagonal close packing (hcp)

Cubic close packing (ccp)

Tetragonal close packing (tcp)

Correct answer:

Hexagonal close packing (hcp)

Explanation:

The figure above represents ABABA packing which is hexagonal close packing.

Example Question #612 : Ap Chemistry

04

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?

Possible Answers:

ZnS

Zn3S

ZnS2

Zn12S4

Zn2S

Correct answer:

ZnS

Explanation:

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 #74 : Compounds And Molecules

 05

What are the names of the alloy types shown in the figure above:

Possible Answers:

 A = Pure Metal; B = Interstitial; C = Substitutional

A = Substitutional; B = Interstitial; C = Pure Metal

A = Interstitial; B = Pure metal; C = Substitutional

None of the above

 A = Pure Meta; B = Substitutional; C = Interstitial

Correct answer:

 A = Pure Meta; B = Substitutional; C = Interstitial

Explanation:

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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