Clicker section + Chapter 12

In which substance, benzene or toluence, are the intermolecular forces stronger? In which substance do the molecular pack more efficiently? a.Benzene possesses stronger intermolecular forces and has molecules packed more efficiently. b.Benzene possesses stronger intermolecular forces, and toluene has molecules packed more efficiently. c.Toluene possesses stronger intermolecular forces and has molecules packed more efficiently. d. Toluene possesses stronger intermolecular forces, and benzene has molecules packed more efficiently

d. Toluene possesses stronger intermolecular forces, and benzene has molecules packed more efficiently

An important difference between crystalline solids and amorphous solids is that crystalline solid have: a. Flat surface b. Variable colors c. Repeating lattice patterns d. Low melting points

c. Repeating lattice patterns

1. The process of vulcanization involves adding which element to natural rubber? a. C b. N c. S d. Zn

c. S

Which of the following statements is (are) true? a. Nonmetallic elements are never found in alloys. b. Interstitial alloys tend to form between elements with similar ionic radii. c. Substitutional alloys tend to be more ductile than interstitial alloys.

c. Substitutional alloys tend to be more ductile than interstitial alloys.

Which element or elements are alloyed with gold to make green gold used in the jewelry industry?

Ag

Silicon readily reacts to form silicon dioxide, SiO2, which is quite hard and is insoluble in water. Is SiO2 most likely a molecular, metallic, ionic, or covalent-network solid?

covalent-network solid?

Adding additional side chains to a monomer to reduce the degree of crystallinity in the polymer is called _____. a. Cleaving b. Coiling c. Condensing d. Cross-linking

d. Cross-linking

Which solid is incorrectly paired with a bonding description? a. Ionic solid, electrostatic attractions b. Metallic solid, delocalized electrons c. Molecular solids, dispersion, dipole and hydrogen bonding d. Network solid, transferred electron.

d. Network solid, transferred electron.

Which of the following is not a solid? a. Ionic b. Molecular c. Metallic d. Superficial

d. Superficial

A material is superconducting if conducts electricity a. Better than insulators do b. Better than a semiconductor do c. Better than metals do d. With no resistance

d. With no resistance

In general, metals are: a. Malleable b. Ductile c. Good conductors of heat and electricity d. D. all of above

D. all of above

What is doping?

Doping is a change in the conductivity of semiconductors by adding an element with more or fewer electrons. - Two type: * n-type (more e): e travel to conduction band => increase conductivity * p-type (fewer e): e travel to valence band => decrease conductivity

Which of the following is not an addition polymer? a. Polyurethane b. Polyethylene c. Polystyrene d. Polyvinyl Chloride

Polyurethane

What are semiconductors?

Substances that can conduct electricity under some conditions but not under other conditions

In an interstitial alloy, the solute radii are____the solvent radii a. Greater b. Equal to c. Less than d. Sequestered by

c. Less than

The types of element whose properties are explained by "band theory" is: a. Metals b. Non-metals c. Metalloids d. Diatomic elements

c. Metalloids

How many atoms are in the face centered cubic cells?

4 atoms

What is the coordination number of each atom in primitive cubic unit cell?

6

What is the coordination number of each atom in body centered cubic unit cell?

8

Which element or elements are alloyed with gold to make white gold used in the jewelry industry?

Ni

What are types of alloys?

- Substitutional: 2 elements have the same sizes - Interstitial alloys: the second element filled a space in the lattice of metal atoms (not equal in size) - Heterogeneous alloy: a mixture of metallic phases (e.g: liquid + solid)

How many atoms are in primitive cubic unit cell?

1 atom

What is the coordination number of each atom in face centered cubic unit cell?

12

How many atoms are in the body centered cubic cells?

2

What is an alloy?

An alloy is a combination of a metal with another metal or nonmetal substance that has been melted and fused together.

Which of the following if doped into silicon would yield an n-type semi-conductor: Ga, As or C? Ga-group 3A As- group 5A C- group 4A

As- group 5A

For molecular solids, the melting point is not determined by the mass of molecules? WHY?

Because as the packing efficiency depends on intermolecular forces. e.g: Benzene, toluene and phenol. => toluene has lower melting point because it is harder to pack.

Which element or elements are alloyed with gold to make rose gold used in the jewelry industry?

Cu

Which element or elements are alloyed with gold to make blue gold used in the jewelry industry?

In

Is Si a molecular, metallic, ionic, or covalent-network solid?

Si is a covalent-network solid.

For metallic structures, does the packing efficiency increases or decreases as number of the nearest neighbors (the coordination number) decreases?

The packing efficiency will Decrease as the number of neighbors decrease.

What are components of semiconductors?

There are two bands in semiconductors: - Conduction band - Valence band - Band gap - Electron must enter the conduction band for electron transfer

Additions polymers require a starting material with _____; condensation polymers require _____? a. Double Bonds; two functional groups b. Two function groups; Double Bonds c. Triple Bonds; delocalized electrons d. Delocalized electrons; Triple Bonds

a. Double Bonds; two functional groups

Which of the following statements are true? a. Inter-metallic compounds have a fixed composition. b. In stainless steel, the chromium atoms occupy interstitial positions. c. Copper is the majority component in both brass and bronze.

a. Inter-metallic compounds have a fixed composition. c. Copper is the majority component in both brass and bronze.

types of crystalline solids

a. Primitive cubic lattices b. Centered cubic lattices c. Body center cubic lattices d. Face center cubic lattices

Which substance below has the weakest intermolecular attractive forces? a. Sucrose b. Sodium Chloride c. Diamond d. Iron

a. Sucrose

1. Which of the following is not an alloy? a. Zinc b. Brass c. Bronze d. Steel

a. Zinc

1. Nanotubes can be made from which element below? a. H b. C c. N d. O

b. C

Which of the following is not a type of cubit unit cell? a. Primitive b. Corner-centered c. Body centered d. Face-centered

b. Corner-centered

The explanation for the differences in properties between ionic and metallic solid is that: a. Ionic solids are often water soluble b. Electrons can move freely in metals, but not in ionic compounds c. The nuclei are in a fixed position in ionic solids, but not in metals d. None are correct.

b. Electrons can move freely in metals, but not in ionic compounds

The integrated circuits in computer are made from materials that are__ a. Conductors b. Semiconductors c. Non-conductors d. Insulators

b. Semiconductors

Covalent bonding occurs in both molecular and covalent-network solids. Which of the following statements best explains why these two kinds of solids differ so greatly in their hardness and melting points? a. Molecular solids are denser than covalent-network solids. b. The molecules in molecular solids are held together by weak intermolecular interactions. c. The atoms in covalent-network solids are more polarizable than those in molecular solids. d. The molecules in molecular solids have stronger covalent bonding than covalent-network solids do

b. The molecules in molecular solids are held together by weak intermolecular interactions.

Which element or elements are alloyed with gold to make blue gold used in the jewelry industry?

intermetallic compounds

Indicate what type of alloy is formed for green gold.

substitutional alloy

Indicate what type of alloy is formed for rose gold.

substitutional alloy

Indicate what type of alloy is formed for white gold.

substitutional alloy