Topic 14: Energy Level System of Solids, Conductors/Semiconductors

Question 1

What are energy bands?

Answer 1

ranges of energy within solids that electrons can be in, (gaps are where they cannot be in)

Question 2

What is used to define semiconductors, conductors and insulators?

Answer 2

band gaps

Question 3

What is a valence band?

Answer 3

where the outermost electrons of an object exist

Question 4

What is a conduction band?

Answer 4

a band of delocalized electrons with great mobility, exist at high enough energy state to be freed from their bond and to ´jump´ the gap in semiconductors and insulators

Question 5

Describe insulators

Answer 5

have large gap between valence and conduction bands almost making it impossible for electrons to reach a high enough energy state to enter conduction band to conduct electricity

Question 6

Describe a semiconductor

Answer 6

small gap between valence and conduction band, little energy required to delocalize electrons to have them enter conduction band

Question 7

Describe a conductor

Answer 7

usually metal: (1) no gap between valence band and conduction band meaning electrons can easily move up conduction band when excited (2) valence band can be filled half way so electrons can conduct in it