Lecture 1

Question 1

solid

Answer 1

important state of matter that is often overlooked in the chemistry curriculum

Question 2

amorphous solids

Answer 2

solids that possess short-range order; NO long-range order present

Question 3

examples of amorphous solids (noncrystalline)

Answer 3

glasses
plastics
gels

Question 4

due to variable long-range order, ?

Answer 4

amorphous solids undergo solid-liquid phase transitions over a wide range of temperatures

Question 5

crystalline solids

Answer 5

solid materials that possess long-range three-dimensional internal order

Question 6

properties of crystalline solids

Answer 6

-exhibit discrete melting points
-more thermodynamically favorable than a disordered state
-formation of an amorphous solid is a kinetic process

Question 7

volcanic glass

Answer 7

-consists of randomly arranged silicate tetrahedrons
-possess tremendous disorder and compositional variation

Question 8

silicate tetrahedrons

Answer 8

short-range order; no long-range order present

Question 9

glass transitions temperatures

Answer 9

temperature below which molecules/ions have very little mobility

Question 10

above Tg (transition temperature)

Answer 10

materials have elasticity

Question 11

below Tg (transition temperature)

Answer 11

materials behave hard and brittle

Question 12

polystrene and methyl merthacrylate used below Tg

Answer 12

glassy hard plastic

Question 13

rubber used above Tg

Answer 13

soft and flexible

Question 14

ionic solids

Answer 14

solid is held together by ionic forces
-ordered array of cations and anions

Question 15

metallic solids

Answer 15

solid is held together by metallic bonds
-delocalized electrons bind metal atoms

Question 16

why is there liquid mercury?

Answer 16

-break down metallic bonds
-very large Zeff
-last element in the 5d series
-less able to share electrons with neighboring metal atoms
-only metal that does not form dimers in the gaseous state

Question 17

network (covalent) solids

Answer 17

solid held together by covalent bonds
-solid consists of sp3 hybridized carbon atoms

Question 18

molecular solids

Answer 18

-solid held together by weak intermolecular forces
-crystal packing of molecules

Question 19

types of molecular solids

Answer 19

-covalent bond: strongest
-ionic bond
-hydrogen bonds
-dipole-dipole
-london forces: weakest

Question 20

lewis structure

Answer 20

arrangement of valence electrons

Question 21

types of structures

Answer 21

-local/defect structure
-unit cell average structure
-nanostructure
-microstructure