Weeks 4-6

Question 1

crystalline solids

Answer 1

atoms, ions or molecules of the material are arranged in a definite repeating pattern

Question 2

amorphous solids

Answer 2

formed when liquids freeze before the molecules are arranged into an orderly position

Question 3

what factor determines if a substance forms a crystalline or amorphous solid

Answer 3

depends of cooling conditions

Question 4

unit cell

Answer 4

the smallest repeating sub-unit of the lattice

Question 5

lattice points

Answer 5

points with identical environments

Question 6

what are the four main types of crystalline solids

Answer 6

1. ionic solids
2. metallic solids
3. Network solids
4. Molecular solids

Question 7

ionic solids

Answer 7

• type of particle: ions
• attraction: ionic bonds
• hard, brittle, high m.p, conducts electricity at a liquid but not solid
• NaCl and Al2O3

Question 8

metallic solids (metals)

Answer 8

• held together by metallic bonding
• hard, strong, electrical conductivity, variable m.p
  -example: copper, iron, lead

Question 9

covalent network solids

Answer 9

• covalent bonds
• very hard, not conductive, high m.p
• SiO3, SiC, C (diamond)

Question 10

covalent networks properties

Answer 10

very hard
not conductive
very high melting points

Question 11

molecular solids

Answer 11

• intermolecular forces
• low mp, brittle, not conductive
• ice, dry ice, table sugar, iodine

Question 12

simple cubic unit cell (primitive cubic)
Polonium structure

Answer 12

atoms per unit cell: 1

CN: 6

Atomic radius: lenght/2

packing efficiency: 52%

Question 13

body centered cubic unit cell

Answer 13

atoms per unit cell: 2
CN: 8
atomic radius: root3 x L = 4r
packing efficiency: 68%
examples: Li, K, Ba, Cr, Mo

Question 14

face centered cubic unit cell

Answer 14

atoms per unit cell: 4
CN: 12
Atomic radius: root2 x L = 4r
packing efficiency: 74%

Examples: Al, Ca, Au, Cu, Pb, Pd, Ni

Question 15

allotrope

Answer 15

different solid state forms that an element can make

Question 16

what are the three carbon allotropes

Answer 16

• graphite
• diamond
• buckministerfullerene

Question 17

lattice systems
- cubic
- tetragonal
- othorhombic
- hexagonal

Answer 17

cubic
- a = b = c
- alpha = beta = gamma = 90 degrees

tetragonal
a=b ≠ c
alpha = beta = gamma = 90 degrees

Orthorhombic
a ≠ b ≠ c
alpha = beta = gamma = 90 degrees

Hexagonal
a=b≠c
alpha = beta = 90
gamma = 120

Question 18

hexagonal and cubic close packing volume efficiency

Answer 18

both 74%

(same as fcc)

Question 19

Gold thiolate (metals in medicine and bio)

Answer 19

used as a treatment for rheumatoid arthritis

Question 20

Calcium (metals in medicine and bio)

Answer 20

is an important component of bones and teeth

Question 21

Lithium compounds (metals in medicine and bio)

Answer 21

are used as a mood stabiliser to treat conditions
including bipolar disorder

Question 22

Technetium (metals in medicine and bio)

Answer 22

is contained in drugs used to treat sleeping sickness

Question 23

Square planar complexes of platinum (metals in medicine and bio)

Answer 23

have anti-cancer activity, interfering with DNA replication in cells

Question 24

Cesium Chloride structure

Answer 24

large anion fills cubic hole at centre
(not the same as bcc as different sizes)

examples: CsBr, CsI, TICl

Question 25

rock salt structure (NaCl)

Answer 25

FCC array of chloride ions with sodium cations in all octahedral holes

all alkali hydrides
AgF, AgCl, AgBr, MgO, CaO, BaO