(13) solid state III

Question 1

What makes a solid an insulator.

Answer 1

if enough electrons are present to fill a band completely, and if there is an energy gap within the lowest unfilled orbital - HOMO AND LUMO

Question 2

what makes Dimond an insulator

Answer 2

all available electrons are used in the strong covenant bonds

both bonding MO and anti bonding MO are filled

Question 3

define a semiconductor

Answer 3

materials whose electrical conductivity increases with temperature

Question 4

define a intrinsic semiconductor

Answer 4

metals which are semiconducting in the pure state

Question 5

define a extrinsic semiconductor

Answer 5

materials which can be doped to become semiconductors

Question 6

describe an n-type semiconductor

Answer 6

adding atoms which have more electrons than the parent atom. This decreases the energy gap so that electrons can easily move into the conduction band when thermal energy is applied

Question 7

name the 2 types of extrinsic semiconductors

Answer 7

n-type semiconductor

p-type semi conductor

Question 8

describe an p-type semiconductor

Answer 8

when you add atoms with less electrons than the parent atom ( they are the LUMO ), therefore decreasing the energy gap between the different bands so when thermal energy is applied electrons can move across a smaller gap.

Question 9

what is the ratio of tetrahedral holes : octahedral holes

Answer 9

for every 2 Tetrahedral : 1 Octahedral