Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CH10133 > solids > Flashcards

solids Flashcards

1
Q

What are crystalline solids?

A

crystalline solids – where atoms or molecules pack together in regular repeating units.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Four main types of solids and examples of each:

A
  • ionic - e.g. NaCl, MgO
  • metal - e.g. Fe, Cu
  • covalent network - e.g. Si, C (diamond)
  • molecular structure - e.g. H2O, I2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why do we have solids?

A

Solid materials are important for fundamental research and technological applications:

Heterogeneous catalysis (e.g. Fe, Pt / CeO2 ) [>80% of industrial chemical production]

Batteries (e.g. LiCoO2 in Li-ion)

Semiconductors (e.g. Silicon chip, Gas) – Solar cells (e.g. Si panels, perovskites CH3NH3PbI3 ).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Two main types of clos packing of atoms:

A

Hexagonal close packing (hcp).

Cubic close packing (ccp).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Hexagonal close packing (hcp): sequence, examples and coordination number:

A

Hexagonal close packing (hcp): layer sequence of ABAB …

Coordination number of each atom = 12 (e.g. Mg, Zn, Tn)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Cubic close packing (ccp): sequence, other name, examples and coordination number:

A

Cubic close packing (ccp): layer sequence of ABCABC…

Coordination number=12 e.g. Copper, nickel, silver, gold

ccp is sometimes called ‘Face Centred Cubic’, FCC - as the structure has atoms on each face

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Body centred cubic (bcc): sequence, examples and coordination number:

A

Body centred cubic (bcc):

Neither hcp or ccp and not as common.

Contains more empty space.

Bcc has a lattice site at the centre of a cube with atoms at the corners with coordination number = 8.

e.g. lithium, sodium, potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are Interstitial sites/holes:

A

Spheres cannot pack without leaving some free space, and this free space is very important in the structures of compounds that are based on close packing but with other atoms or ions in the gaps – this free space is known as interstitial sites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

in ccp and hcp there are two unoccupied types of spaces known as ‘holes’: what are the 2 types?

A

Tetrahedral Hole

Octahedral Hole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a tetrahedral hole?

A

Tetrahedral Hole – Formed by a planar triangle of atoms capped by a single atom (which is surrounded by 4 atoms).

tetrahedral sites lie between a triangle of atoms in one row and a single atom in the other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an octahedral hole?

A

Octahedral Hole – Lies between two oppositely directed planar triangles of atoms. The single atom in the hole would be surrounded by 6 atoms.

octahedral sites lie between a triangle of atoms in the row above and another triangle of atoms in the row below.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a unit cell?

A

the smallest repeating unit that shows the full symmetry of the solid structure - which repeats in 3D to give an infinite solid lattice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a Cell projection diagram?

A

2D representations of unit cells viewed from above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are crystal structures determined?

A

X-ray crystallography.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are ionic solids?

A

Ionic solids can be considered an assembly of oppositely charged ions with strong electrostatic interactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the radius ratio equation?

A

radius rate = r+ / r-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

packing efficiency equation?

A

volume of the atoms in a unit cell / total volume in a unit cell x 100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How to find the volume of a unit cell:

A

4/3 x pi x radius^3

19
Q

What is a band in the band theory?

A

For a solid - the gap between that many energy levels is so close that they form a continuum of energy levels – called a band

20
Q

What is a band gap?

A

The energy difference between bands is the Band Gap

21
Q

What is a conduction band?

A

a partially filled or empty band, which allows electronic conductivity

22
Q

Differences between a metal, semiconductor and insulator depend on:

A

Band structure
Whether valence bands are full of electrons or not
Size of the band gap (between full and empty bands).

23
Q

What is the highest filled energy level in a metal known as?

A

Highest filled energy level is called the Fermi Level

24
Q

In metals, why does the conductivity decrease with increasing temperature?

A

Conductivity decreases with increasing temperature due to atomic vibrations and electronic scattering

25
Q

In a semiconductor, what band is full and what band is empty?

A

Valence band is full.

Conduction band is empty.

26
Q

In a semiconductor, is the band gap typically big or small?

A

Band gap is small

27
Q

In a semiconductor, what does the size of the band gap lead to?

A

Small band gap → allows electrons to be promoted (‘jump’) over the band gap into the empty conduction band - if they have enough thermal energy

28
Q

In a semiconductor, why does the conductivity increase with increasing temperature?

A

Conductivity increases with temperature due to a greater population of mobile electrons in the upper conduction band - allowing high electronic conductivity.

29
Q

In a insulator, what band is full and what band is empty?

A

Valence band is full.

Conduction band is empty

30
Q

In a insulator, is the band gap typically big or small?

A

the band gap is large

31
Q

In a insulator, what does the size of the band gap lead to?

A

Large band gaps lead to a very limited (or no) electron population in the upper band → hence poor (or no) electronic conduction.

32
Q

Where do point defects occur?

A

Point defects – occur at single lattice sites.

33
Q

What is a vacancy?

A

empty lattice site.

34
Q

What is an Interstitial?

A

ion at a site not normally occupied.

35
Q

What is a Dopant (or impurity)?

A

ion substituting at a lattice site - deliberately added

36
Q

Why are defects important?

A

Because they often influence solid state properties.

37
Q

What is a Schottky Defect?

A

A pair of vacancies (anion and cation) found in alkali halides (NaCl, KBr) and some binary oxides (MgO, CaO)

38
Q

Kroger - Vink: Defect notation explanation

A 
V = vacancy
Subscript = element
Superscript = effective charge.
39
Q

What is a Frenkel Defect?

A

Atom or ion displaced off its lattice site into a site not normally occupied (interstitial site) leaving a vacancy e.g. AgCl (rocksalt).

40
Q

What is an allotrope?

A

Different structural forms of the same element. For example: diamond, graphite, Buckminster fullerene

41
Q

What is a polymorph?

A

Different crystal structures of the same compound.

42
Q

In solid state structures, what is the coordination number defined as?

A

The number of nearest neighbours an atom has.

43
Q

What coordination number does both cubic and hexagonal close-packed structures have?

A

12

CH10133 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions