Chapter 12- Solids

Question 0

Ionic solids

Answer 0

Sets of cations and anions mutually attracted to one another
- very high melting and boiling pts
Ex: NaCl and MgO
Ionic bonds

Question 1

Metallic solids

Answer 1

Network of highly delocalized electrons
-allows metals to conduct electricity
- also responsible for most metals being strong but not brittle
- malleable and ductile
Example: Cu, Fe
- metallic bonds

Question 2

Covalent network solids

Answer 2

Joined by expensive networks of covalent bonds
- tend to be hard and have high melting pts
Ex: diamonds, C and Si
Covalent bonds

Question 3

Molecular solids

Answer 3

Discrete molecules that link to one another only by VDW forces and hydrogen bonds

• soft and low melting points
• HBr, H2O

Question 4

Crystalline solids

Answer 4

Atoms arranged in a very regular pattern

Ex: chloride, quartz, and diamond

Question 5

Amorphous solids

Answer 5

Characterized by distinct lack of order in the arrangement of atoms
- rubber, glass and obsidian

Question 6

Crystal lattices

Answer 6

Lattice is repeated pattern

Unit cell is why is repeated

Question 7

Face centered cubic cell

Answer 7

4 atoms total

74% packing efficiency

Question 8

Body centered cubic cell

Answer 8

2 atoms total

68% packing efficiency

Question 9

Alloys

Answer 9

Combinations of two or more elements majority of which are metals

Question 10

Substitutional alloy

Answer 10

2nd element takes the place of metal atom

Question 11

Interstitial ally

Answer 11

2nd element fills a space in lattice of metal atoms

Question 12

Polymers

Answer 12

Contain long chains of atoms connected by covalent bonds

- stronger and higher melting points than molecular solids and more flexible

Question 13

Cubic lattices

Answer 13

-primitive or lattice or at each corner
Or 
- body centered/ corners and center
Or 
- face centered/ corners and faces

Question 14

Primitive cubic metal

Answer 14

1 atom per unit cell

Question 15

Coordination number

Answer 15

Number of neighbor atoms

of cations/ # of anions

Question 16

Bond order of Molecular orbital theory

Answer 16

1/2(bonding MO- antibonding MO)

Question 17

Why does melting points rise then fall when going across the periodic table?

Answer 17

MO theory explains that the # of valence e rise to full bonding and strength the bonds but once it is full the melting point falls

Question 18

Semiconductor

Answer 18

Only group IVA (4 valence electrons)

Covalent network solid

Question 19

Doping

Answer 19

Increases conductivity
Use element with valence electrons to use as doping agent
Fewer valence e - p type
More valence - n type

Question 20

Polymers

Answer 20

Molecules of high molecular mass made by sequentially bonding repeating units called monomers

Question 21

Addition polymers

Answer 21

Made by coupling the monomers by converting a pi bond within each monomer to a sigma bond

Question 22

Condensation polymer

Answer 22

Made by joining subunits through a reaction in which a smaller molecule (often water) is also formed as a by product
Ex: amino acid and nylon

Question 23

Properties of polymers

Answer 23

Interactions between chains of a polymer lend elements of order to the structure of polymers

Question 24

Stretching a polymer

Answer 24

Can increase the amount of order and lead to a degree of crystallinity

Question 25

Cross linking polymers

Answer 25

Chemically bonding chains of polymers can stiffen and strengthen the substance

Vulcanization of rubber leads to stronger substance