Chapter 1: Bonding, Structure, And Defects

Question 1

What happens to the size of an anion and a cation when it gains/lose electrons?

Answer 1

• Anions get bigger

- Cations get smaller

Question 2

Where in the periodic table do we have the most electronegative elements?

Answer 2

Top right (Fluorine)

Question 3

What sort of bonds exists?

Answer 3

• Metallic
• Covalent
• Ionic

Question 4

What would the bonding type of P_4O_10 be?

Answer 4

Covalent oxide (small electronegativity difference)

Question 5

What is the oxidation number of F?

Answer 5

-1

Question 6

What is the oxidation number of O?

Answer 6

-2 (oxide)
-1 (peroxide)
-1/2 (superoxide)
(Except in a bond with F)

Question 7

What is the oxidation number of H?

Answer 7

+1 (proton) or -1 (hydride)

Question 8

What sort of packing does a hexagonal close-packing (hcp) have?

Answer 8

ABABABAB …..

Question 9

Which is the closest packing of the cubic structure?

Answer 9

Face centered packing

Question 10

What sort of packing does a cubic close-packing (ccp) have?

Answer 10

ABCABCABC …

Question 11

What types of holes exists?

Answer 11

Octahedral and tetrahedral

Question 12

What sort of parameters are there for tetrahedral holes?

Answer 12

• Surrounded by 4 large spheres
• Relatively small
• 2 per sphere

Question 13

What sort of parameters are there for octahedral holes?

Answer 13

• Surrounded by 6 large spheres
• Relatively large
• 1 per sphere

Question 14

What is the packing and filling of the rocksalt structure? (AX)

Answer 14

Fcc with all octahedral holes filled

Question 15

What is the packing and filling of the fluorite structure? (AX_2)

Answer 15

• Fcc of A[2+] with X[-1] in all tetrahedral voids

OR

• Simple cubic X[-1] with A[2+] in every other cube

Question 16

What is the packing and filling of the perovskite structure? (ABX_3)

Answer 16

Fcc of A[+3]X with B in octahedral voids in-between AX_6 units

Question 17

What is the conduction and the valence band?

Answer 17

• Conduction band: lowest unoccupied band

- Valence band: highest occupies band

Question 18

How is the band gap defined?

Answer 18

• Energy range where no electron states can exist

- The energy difference between CB and VB

Question 19

What sorf of defects are there?

Answer 19

• Point defects (0D)
• Line defects (1D)
• Planar defects (2D)
• 3D

Question 20

What are the point defects?

Answer 20

• Interstitials (in- and extrinsic)
• Vacancies
• Substitutional

Question 21

What are the line defects? [NEEDS EDITING]

Answer 21

• Edge dislocation

-

Question 22

What are the planar defects?

Answer 22

• Plane of point defects
• Row of dislocation
• Grain boundary

Question 23

What are the Kröger-Vink notation for an oxygen and a metal vacancy?

Answer 23

• v_O++

- v_M’’ (divalent)

Question 24

What is an effective charge?

Answer 24

It is the actual charge of the species minus the actual charge that the ideal perfect reference structure would have had in the same structural element

Question 25

What would the effective charge of a metal vacancy be?

Answer 25

Negative the oxidation state

Question 26

How would you describe an oxidized metal, e.g. Ni2+ to Ni3+?

Answer 26

As a hole, h+

Question 27

How would you describe a reduced metal, e.g. Ni2+ to Ni1+?

Answer 27

As an electron, e-

Question 28

How is a proton described using the K-V notation? (in an oxide)

Answer 28

As an hydroxide ion subst. an oxide ion ==> OH_O+ | NOT as a single positively charged interstitial H

Question 29

Why aren't the single proton described as such in the K-V notation? (in an oxide)

Answer 29

Because it will be drawn into the electron cloud of an anion close by

Question 30

How are the effective positive and negative charges in an ionic compound related?

Answer 30

They have to be compensating each other fully, as an ionic compound has to be electrically neutral

Question 31

In the elctroneutrality condition, what sort of concentration is used here?

Answer 31

Charge concentration, not species

Question 32

What sort of defects appear in a stoichiometric compound?

Answer 32

Schottky, Frenkel, and anti-site defects (swap cation/anion)