343 Exam 1

T/F. The angular momentum number defines orbital shape.

T

T/F. Dipole-dipole forces are stronger than hydrogen bonds.

F

T/F. Calcium (Ca) is larger in size versus Ca2+

T

T/F. Oxygen always has 16 protons.

F

T/F. The ionic character of a covalent bond is determined by the difference in size of bonding atoms.

F

T/F. Bromine (Br) is larger in size versus bromide (Br-).

F

T/F. Hydrogen bonding exists between ammonia molecules (NH3).

T

T/F. Ionic bonding is non-directional.

T

T/F. The % ionic character of C-N bonds is greater than that of C-O bonds.

F

T/F. When the angular momentum number l=2, there are 3 different atomic orbitals.

F

T/F. "Toughness" is the ability of a material to resist deformation.

F

T/F. Deuterium and protium each have 1 proton, thus they are isotopes of hydrogen.

T

T/F. As the angular momentum number increases, the electron energy increases.

T

T/F. The 5s orbital fills with electrons before the 4d orbital.

T

T/F. Polypropylene (PP), a hydrocarbon polymer, will experience London forces between polymer chains.

T

T/F. Bioactive glasses and glass-ceramics are characterized by a low CaO/P2O5 ratio.

F

T/F. The stacking sequence of an HCP crystal structure is "ABAB".

T

T/F. The atomic packing factor of HCP is lower than that of BCC.

F

T/F. Crosslinked polymers may be "melted and re-shaped".

F

T/F. For a synthetic polymer sample, as the PDI increases, the difference between the number average molecular weight and the weight average molecular weight decreases.

F

T/F. The coordination number of FCC is 12.

T

T/F. The zinc blend (ZnS) crystal structure has a cation coordination number = 6 and an anion coordination number = 6.

F

T/F. Ceramics exhibit covalent bonding.

F

T/F. Both linear and branched polymers can be covalently crosslinked to form thermosetts.

T

T/F. FCC belongs to the cubic crystal system.

T

T/F. Bioactive glass 45S5 has a melt transition.

F

T/F. Nylon 6,6 is a polyester.

F

T/F. For ceramics, as the coordination number (CN) of the cation increases (an the anion size stays the same), the size of the cation must decrease.

F

T/F. Miller indices are represented as (h, k, l).

F

T/F. For a ceramic, a cation coordination number of 8 coincides with a cubic coordination geometry.

T

When a biomaterial elicits intentional effects on living tissues, which of the following best describes them?

Bioactive

Crystalline ranges

highly crystalline: 90-70% semi-crystalline: 80-20% amorphous: 0% crystalline: 100%

Polydispersity Index (PDI) Equation

Mw/Mn, PDI > 1 (always)

Tm ___ Tg

Tm > Tg (always, unless no Tm)

Tg definition

Temperature at which there is an increase in segment mobility of the polymer backbone

Why are some polymers biodegradable

Hydrophilic ester groups experience hydrolysis and break bonds

Why are some polymers with esters not biodegradable

Large aromatic carbons

Biodegradable polymers

PGA PLLA PDLLA PDS PCL

Highly crystalline polymers

HDPE Isotactic PP Isotactic PS PTFE

Amorphous polymers

Atactic PP Atactic PS PMMA PHEMA PC PDLLA

Si-O bonds % ionic character

51%

Fluorite (CaF2) A and X CN

A: 8 X: 4

Zinc Blend (ZnS) A and X CN

A: 4 X: 4 Td coordination geometry

Cesium Chloride (CsCl) A and X CN

A: 8 X: 8 cubic coordination geometry

Rock Salt (NaCl) A and X CN

A: 6 X: 6 Oh coordination geometry

Linear coordination geometry CN

2

Triangular coordination geometry CN

3

Td coordination geometry CN

4

Oh coordination geometry CN

6

Cubic coordination geometry CN

8

crystallographic plane (Miller indices)

( h k l )

crystallographic directions

[ u v w ]

point coordinates

q r s

HCP APF

0.74, close packed

HCP CN

12

Number of atoms in 1 HCP unit cell

6

BCC APF

0.68

BCC CN

8

Number of atoms in 1 BCC unit cell

2

FCC APF

0.74, close packed

FCC CN

12

Number of atoms in 1 FCC unit cell

4