The resistivity (a measure of electrical resistance) of...

The resistivity (a measure of electrical resistance) of graphite is $(0.4 \text { to } 5.0) \times 10^{-4}$ ohm $\cdot \mathrm{cm}$ in the basal plane. (The basal plane is the plane of the six-membered rings of carbon atoms.) The resistivity is 0.2 to 1.0 ohm $\cdot \mathrm{cm}$ along the axis perpendicular to the plane. The resistivity of diamond is $10^{14}$ to $10^{16} \mathrm{ohm} \cdot \mathrm{cm}$ and is independent of direction. How can you account for this behavior in terms of the structures of graphite and diamond?

Key Concepts

Resistivity

Resistivity is a fundamental property that measures how strongly a material opposes the flow of electric current. It is influenced by the material's structure, bonding, and the availability and mobility of charge carriers within the material.

Crystal Structure

Crystal structure refers to the ordered arrangement of atoms in a material, which significantly affects its physical properties. The different arrangements of atoms in various materials result in diverse pathways for electron conduction, thereby impacting their resistivity.

Anisotropy in Electrical Properties

Anisotropy is when a material exhibits direction-dependent physical properties. In the context of electrical conductivity, anisotropy means that electrons may move more easily in certain crystallographic directions over others due to differences in atomic bonding and structural organization.

Bonding and Electron Delocalization

Bonding and the degree of electron delocalization play crucial roles in determining electrical behavior. In structures where electrons are delocalized, such as in planar networks with conjugated systems, electrical conduction is enhanced along those directions. In contrast, structures with localized electrons, due to strong directional bonds, tend to exhibit poor electrical conductivity.

Transcript

00:01 So in this video we're going to go over question 82 from chapter 20, which says the resistivity, a measure of electrical resistance of graphite, is 0 .4 to 5 .0 times 10 to negative 4 oam centimeters in the basal plane.

00:16 The basal plane is the plane of the six -membered rings of the carbon atoms.

00:19 The resistivity is 0 .2 to 1 omeatometers along the axis perpendicular to the plane.

00:26 The resistivity of diamond is 10 to the 14th to 10 to the 16th.

00:30 Ome centimeters and is independent of direction.

00:35 How can you account for this behavior in terms of the structure of diamond? so basically we're told that graphite has the lowest resistance, meaning it's the best conductor in the basal plane, and then it's a slightly worse conductor in the axis perpendicular to the basal plane, and then diamond is an even poorer conductor, has an even higher resistivity.

01:02 So let's go over what the structures of diamond and graphite are, and we'll talk about how those can account for these resistivities.

01:09 So the structure of diamond is this tetrahedral lattice, where each carbon is the center of a tetrahedron, and each carbon is bonded to four other carbon atoms.

01:20 So you have this tetrahedral lattice in which all of our valence electrons of our carbon atoms are tied up in these bonds and these bonds making up the lattice.

01:31 So all of our electrons are already occupied.

01:34 So it might make sense that diamond would have a high resistivity and be a poor conductor because it doesn't have any valence electrons to travel throughout the lattice because they're all tied up in the bonds...

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