Ch 12

Question 1

Name and describe the four classifications of solids

Answer 1

• Metallic solids: Networks of atoms with ‘metallic bonding’
• Ionic solids: Networks of ions held together by ion-ion interactions
• Molecular solids: molecules are held together by intermolecular forces
• Covalent-network solids: networks of atoms held together by covalent bonds

Question 2

term: a solid that lacks order and repeating patterns

Answer 2

Amorphous

similar structure to liquids, but lack their freedom of motion

Question 3

term: solids that are arranged in orderly repeating patterns

Answer 3

Crystalline

usually feature flat surfaces and regular shapes

Question 4

the structure of a crystalline solid is defined by:

Answer 4

• the size and shape of the unit cell

- the location of atoms within it

Question 5

crystal lattice

Answer 5

the scaffolding of the geometric points on which unit cells are arranged

Question 6

how many shapes work in a 2-D lattice?

Answer 6

4

Question 7

how many shapes work in a 3-D lattice?

Answer 7

7.

Question 8

primitive lattice

Answer 8

only place lattice points at each corner of the unit cell

Question 9

term: lattice points at corners plus one lattice point in center of unit cell

Answer 9

body centered lattice

Question 10

term: lattice points at corners plus one lattice point at the center of each face

Answer 10

face-centered lattice

Question 11

4 classes that alloys can be broken down into

Answer 11

• Substitutional: solute atom can occupy solvent atoms
• Interstitial: solute atoms can occupy the space between solvent atoms
• heterogeneous: components are not dispersed uniformly
• intermetallic compounds: not a mixture, but a compound of >1 element

Question 12

Electron-sea model;

what does it explain?

Answer 12

electrons are:
-uniformly distributed
-mobile
explains:
-electrical conductivity
-thermal conductivity
-malleability/ductility
poorly explains:
-metallic bond strength and melting point

Question 13

molecular-orbital model

Answer 13

as more metal atoms bond in a chain more molecular orbitals are generated

Question 14

band structure

Answer 14

the electronic structure of a solid which usually consist of a series of bands

Question 15

• ionic solids are held together by:

- strength depends on:

Answer 15

• electrostatic attraction

- charge, size of ions

Question 16

why are ionic compounds typically brittle?

Answer 16

due to repulsive interactions between ions of like charges

Question 17

(can/can’t)
ions of opposite charge ___ touch each other.
ions of like charge ____ touch each other.

Answer 17

can

can’t

Question 18

there is a unit cell with 8 calcium on the corners, 1 titanium in the middle, and 6 oxygen on the faces. what are the coordination numbers?

Answer 18

81/8=1ca
11=1 Ti
6*1/2= 3 O

Question 19

use the anion coordination number to determine the Al3+ coordination number for AlF3 (F= 2 coordinate)
AIN (N =4 coordinate)

Answer 19

1Al/3F = 1cat/3 an = 2/x. x=6

1Al/1N = 4/x x=4

Question 20

metallic solids are held together by

Answer 20

a delocalized sea of electrons

Question 21

ionic solids are held together by

Answer 21

mutual electrostatic attraction between cations and anions

Question 22

covalent network solids are held together by

Answer 22

an extended network of covalent bonds

Question 23

molecular solids are held together by

Answer 23

intermolecular forces

Question 24

is Si a covalent, metallic, ionic or molecular bond?

Answer 24

covalent