2 Atomic Structure and Material Microstructure Free Online FlashCards

How does metallic bonding help explain metal conductivity and deformation?

Valence electrons move readily throughout the solid, helping many metals conduct heat and electricity and allowing atoms to rearrange during deformation.

Why are many ionic solids brittle?

Shifting atomic planes can bring like-charged ions together, making many ionic solids brittle.

How can covalent bonding affect a material’s hardness and deformation?

Its strong, directionally preferred bonds create a hard, stiff network but can limit deformation.

How do strong and weak bonds coexist in polymers?

Strong bonds can hold atoms along a polymer chain, while weaker attractions hold different chains or chain segments together.

What is a unit cell?

A unit cell is the smallest repeating description of a crystal’s structure.

What distinguishes one grain in a polycrystalline material?

A grain is a region in a polycrystalline material with a consistent crystal orientation.

What is texture in a polycrystalline material?

Texture is a preferred orientation shared by many grains; it can make a material behave differently in different directions.

How does a glass differ from a crystal in atomic arrangement?

Glasses lack long-range repeating order.

How do vacancy, interstitial, and substitutional point defects differ?

A vacancy is a missing atom, an interstitial occupies a normally unoccupied space, and a substitutional impurity replaces a host atom.

What is doping in a semiconductor?

Doping deliberately adds impurities to tune a semiconductor’s properties.

What role do dislocations play in metal plastic deformation?

Dislocations are line defects that move through crystals as metals undergo plastic, permanent deformation.

What are two contrasting effects of grain boundaries?

They can impede dislocation motion, but they can also provide diffusion paths or sites where impurities collect.