Conductivity

Question 1

As the number of atoms in the cluster increases, the spacing between the energy levels of the various orbitals _______.

Increases or decreases

Answer 1

Decreases

Question 2

Those materials in which an electric current flows easily in one specific crystal direction while the resistivity is very high in transverse directions

Answer 2

One-dimensional conductors ​​

Question 3

A completely filled valence band separated from the next energy band, which is empty, by a large, forbidden gap​

Answer 3

Insulators​

Question 4

The band made up of the occupied molecular orbitals and is lower in energy than conduction band.

Answer 4

Valence Band

Question 5

The band of orbitals that are high in energy and are generally empty.

Answer 5

Conduction Band

Question 6

Are materials that are simialr to metals except that they have poorer conductivity and are not malleable like metals.

Answer 6

Semi-Metals

Question 7

A type of extrinsic semiconductor where the dopant atoms are capable of providing extra holes to the host material.

Answer 7

p-type Semiconductors

Question 8

A type of extrinsic semiconductor where the dopant atoms are capable of providing extra conduction electrons to the host material which creates an excess of negative (n-type) electron charge carriers.​

Answer 8

n-type Semiconductors

Question 9

Are pure materials where the number of electrons in the conduction band is determined only by the size of the band gap and the temperature (more electrons with small band gap and high temperature).

Answer 9

Intrinsic Semiconductors

Question 10

Are materials where the conductivity is controlled by adding dopants with different numbers of valenece electrons to that of the original material.

Answer 10

Extrinsic Semiconductors

(e.g. Germanium doped with Phosphorous [valance of 5])

Question 11

The band gap is not very large and some electrons have sufficient thermal energy to be promoted up to the empty conduction band.

Answer 11

Semiconductors

(e.g pure elements, such as silicon or germanium, or compounds such as gallium arsenide or cadmium selenide​)

Question 12

The conductivity of this class of materials is increased, when the temperature is increased.

Answer 12

Insulators

There is a large energy gap between the valance and conduction bands​, so large that valance electrons barely populate the conduction bands and thefore do not impede electron flow.

Question 13

Property of complete disappearance of electrical resistance in solids when they are cooled below a characteristic temperature

Answer 13

Superconductivity

Question 14

The minimum photon energy required to excite an electron up to the conduction band from the valence band.

Answer 14

Band gap​

Question 15

Valence electrons can move through this class of material and are unique as good conductors of electricity.

Answer 15

Metals

Question 16

At absolute zero temperature intrinsic semiconductor acts as perfect insulator.

True or False

Answer 16

True

Question 17

A completely filled level (the valence band) and an empty one (the conduction band) separated by a band gap.

Answer 17

Leads to Non-metallic behavior

Question 18

A partially filled band, no gap between the top filled level (Fermi level) and the lowest empty one.

Answer 18

Leads to Metallic behavior