Chapter 12

Question 1

What is a Crystalline Lattice (of solid)?

Answer 1

any arrangement of atoms in a crystalline solid.

Question 2

What is a Unit Cell?

Answer 2

A small piece/collection of atoms, ions, molecules. Focus on Cubic unit cells!

Question 3

What are the 3 types of Cubic Cells?

Answer 3

Simple Cubic, Body-Centered Cubic, and Face-Centered Cubic.

Question 4

Simple Cubic:

Answer 4

1 atom on each corner: l=2r

Question 5

Body-Centered Cubic:

Answer 5

1 atom on each corner, 1 atom in center of cube;

l=4r/sqrt3

Question 6

Face-Centered Cubic:

Answer 6

1 atom on each corner, 1 atom on center of each cube face. l=2*sqrt2r.

Question 7

Coordination Number:

Answer 7

The number of atoms with which each atom is in direct contact.

Question 8

What are Closest-Packed Structures? What are the 2 types?

Answer 8

Stacking atoms on top of one another; more conceptual!

Hexagonal Closest Packing and Cubic Closest Packing.

Question 9

Hexagonal Closest Packing and Cubic Closest Packing:

Answer 9

Just have to look at the examples in the book!!! ch.12!

Question 10

What are Molecular Solids?

Answer 10

Solids that are composed of molecules. The Lewis Structure plays a large role in stability.

Question 11

What are Ionic Solids? Melting points?

Answer 11

Cations and Anions (salt) held together by ionic bonds. High melting points!

Question 12

What are Atomic Solids?

Answer 12

Composite particles of individuals atoms. Each version of atomic solids are held together by a different force!

Question 13

If a question on the 3 Atomic Solids, Week 14 Ch. 12 Notes!!!

Answer 13

YES.

Question 14

Differences between Unit Cells and Ionic Solids?

Answer 14

There are Cations and Anions in Ionic solid structures, as opposed to just one atom.

Question 15

What is Coordination Number? How does it relate with atomic radii

Answer 15

Max interactions between cations and anions. Larger atomic radii restrict coordination number. EX- NaCl, large Cl.

Question 16

How are unit cells affected by the charge ratio?

Answer 16

When the ratio is not 1:1 in a molecule, etc., must accommodate new ratio to keep charge neutrality.

Question 17

What do Network Covalent Atomic Solids have? What are some examples?

Answer 17

Some of the highest melting points of all substances. Carbon and its different forms/allotropes, etc.

Question 18

What are some Carbon based forms/allotropes?

Answer 18

Graphite, Coal, Diamond, Fullerenes, Nanotubes, etc.

Question 19

What are carbon nanotubes?

Answer 19

Carbon6 rings in hexagonal shape, shaped as a tube. There are Single walled (SWNT) and Multi-walled (MWNT) nanotubes.

Question 20

What can be done with Multi-walled nanotubes (MWNT)?

Answer 20

They can be “cut up” into Graphene nanoribbons. This is what carbon fiber is!

Question 21

What are silicates, why are they unique?

Answer 21

Molecules compose 90% of earths core. They have one lone electron on the Oxygen.

Question 22

What is the difference between valence bonds and conduction bonds?

Answer 22

Valence bonds are occupied/ bonding orbitals. Conduction Bonds are empty/ anti-bonding orbitals.

Question 23

What is a Band Gap?

Answer 23

The energy required for an e- to be promoted from valence to conduction.

Question 24

What are the 3 types of band gaps?

Answer 24

Conductor: NO energy gap.
Semiconductor: Small energy gap.
Insulator: Large energy gap.

Question 25

How band gaps relate to periodic table and conductivity trend? Why? Pg.556

Answer 25

As you move down the periodic table, band gaps decrease! because atomic radii, and the reduced overlap between orbitals and neighboring atoms.

Question 26

What is Doping Semiconductors?

Answer 26

artificially make semiconductors better conductors or electricity.

Question 27

What are P-Type Semiconductors? How are they created?

Answer 27

They are made by doping with Gallium. The Gallium atoms trap some e- in valence bonds, resulting in ‘holes’. Each hole acts as a positive charge.

Question 28

What are N-Type Semiconductors? What are they doped with?

Answer 28

Charge carriers are negatively charged e- in conduction bond. Doped with Phosphorus.

Question 29

How are Polymers created?

Answer 29

They can be formed through Addition OR condensation polymerization.

Question 30

How do Monomers and Polymers relate?

Answer 30

Polymers are long, chainlike and composed of repeating units called monomers.

Question 31

Addition VS Condensation reactions:

Answer 31

Addition: Monomers link together without elimination of any atoms.
Condensation: a monomer with an exposed H atom binds with a monomer w/ an exposed OH atom(s)