EXAM 3 ch 12 Flashcards
(33 cards)
Quartz, a form of SiO2, which contains an ordered array of neutral, covalently bonded nonmetal units, is an example of
a molecular solid.
an ionic solid.
a metallic solid.
an amorphous solid.
an alloy.
a molecular solid
Obsidian, a form of SiO2, which contains no long-range ordering of any kind and is made up of bonded nonmetal units, is an example of
a molecular solid.
an ionic solid.
a metallic solid.
an amorphous solid.
an alloy.
an amorphous solid
Copper has a face-centered cubic unit cell. Which element do you also expect to have a face-centered cubic unit cell?
Na
K
Ti
Mg
Ag
Ag
Arrange the following metals in order of expected increasing density. All have a face-centered cubic unit cell.
Ni, Pd, Pt
Pt < Pd < Ni
Pt < Ni < Pd
Pd < Pt < Ni
Pd < Ni < Pt
Ni < Pd < Pt
Ni < Pd < Pt
What type of crystal structure produces an aaaaaa layering pattern?
hexagonal
body-centered cubic
face-centered cubic
hexagonal or body-centered cubic
simple cubic
simple cubic
n the sodium chloride unit cell, the chloride ions form a cube in which each side is arranged like the following figure. The circles represent the positions of the chloride ions on one square face of the cube. All the other faces are the same. What is the name of this unit cell?
simple cubic
x-face cubic
chloride-centered cubic
body-centered cubic
face-centered cubic
face-centered cubic
Which of the following statement(s) about the simple cubic unit cell is(are) correct?
It results from the square packing of atoms in layers.
The atoms lie at the corners of a cube.
Each atom has 6 nearest neighbors.
The stacking pattern can be represented by aaaa.
All these statements are correct.
All these statements are correct
In the cesium chloride unit cell shown, the cesium ions sit on the corners of a cube. What is the name of this unit cell?
simple cubic
cubic-centered
chloride-centered cubic
body-centered cubic
face-centered cubic
body-centered cubic
Which of the following unit cells has the lowest packing efficiency?
simple cubic
face-centered cubic
body-centered cubic
both face-centered and body-centered cubic
Simple, face-centered, and body-centered cubic all have the same packing efficiency.
simple cubic
Which of the following unit cells has the highest packing efficiency?
simple cubic
face-centered cubic
body-centered cubic
both face-centered and body-centered cubic
Simple, face-centered, and body-centered cubic all have the same packing efficiency.
face-centered cubic
How many nearest neighbor atoms are there around each atom in a simple cubic unit cell?
4
10
6
12
8
6
How many nearest neighbor atoms are there around each atom in a face-centered cubic unit cell?
4
10
6
12
8
12
How many nearest neighbor atoms are there around each atom in a body-centered cubic unit cell?
4
10
6
12
8
8
An atom in a particular unit cell has 8 nearest neighbor atoms around it. Which unit cell(s) is(are) possible?
simple cubic
hexagonal
body-centered cubic
face-centered cubic or hexagonal
face-centered cubic
body-centered cubic
Polonium crystallizes in a simple cubic pattern. How many polonium atoms are in each unit cell?
1
4
2
5
3
1
Iron crystallizes in a body-centered cubic pattern. How many iron atoms are in each unit cell?
1
8
2
9
4
2
Copper crystallizes in a face-centered cubic pattern. How many copper atoms are in each unit cell?
2
12
4
14
8
4
Silver crystallizes with a face-centered cubic unit cell. The edge length is 408 pm. What is the volume of this unit cell?
7.68 × 107 pm3
9.87 × 107 pm3
6.79 × 107 pm3
3.88 × 107 pm3
8.67 × 107 pm3
6.79 × 107 pm3
Nickel (Ni) crystallizes as a face-centered unit cell with an edge length of 382 pm. What is the atomic radius of nickel?
135 pm
252 pm
165 pm
1080 pm
191 pm
135 pm
Iron (Fe) crystallizes as a body-centered unit cell and has an atomic radius of 126 pm. What is the edge length for the unit cell of iron?
55 pm
291 pm
63 pm
356 pm
252 pm
291 pm
Gold has a face-centered cubic structure with a unit cell edge length of 407.8 pm. What is the contribution to the density from each individual gold atom?
21.44 g/cm3
6.55 g/cm3
26.20 g/cm3
19.28 g/cm3
13.1 g/cm3
19.28 g/cm3
Which statement regarding the formation of an alloy is correct?
Carbon forms an interstitial alloy with iron because their atomic radii are about the same.
Carbon forms a substitutional alloy with iron because their atomic radii are about the same.
Carbon forms an interstitial alloy with iron because carbon has a much smaller atomic radius.
Carbon forms a substitutional alloy with iron because carbon has a much smaller atomic radius.
Carbon forms an interstitial alloy with iron because carbon has a much larger atomic radius
Carbon forms an interstitial alloy with iron because carbon has a much smaller atomic radius.
Which of the following refers to an alloy in which the composition is variable and the elements have comparable radii?
intermetallic
substitutional
interstitial
homogeneous
stoichiometric
substitutional
In addition to carbon and iron, stainless steel contains
teflon and polyethylene.
chromium and nickel.
gold and silver.
platinum.
copper and nickel.
chromium and nickel.
