Crystal Structures, Bonding, and XRD Review

These flashcards cover key vocabulary and concepts related to crystal structures, bonding, and X-ray diffraction as outlined in the lecture notes.

Bonding types

Metallic, covalent, ionic, van der Waals, and hybrid types of bonding.

Crystal systems

There are seven crystal systems: cubic, tetragonal, orthorhombic, hexagonal, rhombohedral, monoclinic, triclinic.

Phosphorescence

A phenomenon causing materials to glow in the dark.

Miller indices

A notation system to describe the orientation of planes in a crystal.

Bragg’s Law

nλ = 2 d sinθ; a formula that relates the angles of scattered X-rays to the structure of a crystal.

Coordination number

The number of nearest neighbors surrounding a central atom.

Diamond cubic structure

A crystalline structure with 8 atoms per unit cell.

Interplanar spacing formula

d(hkl) = a / √(h² + k² + l²), used to calculate the distances between atomic planes in a crystal.

X-ray diffraction (XRD) peaks

Caused by constructive interference of X-rays from atomic planes.

Elastic modulus

A measure that reflects the stiffness of a material, related to the shape of the bond energy curve.

Covalent bond

A directional bond formed by the sharing of electrons between atoms.

Van der Waals bond

A type of weak intermolecular bond that does not involve sharing of electrons.

Cubic packing efficiency

FCC & HCP pack with 74% efficiency while BCC packs with approximately 68%.

Primitive cell

The smallest repeat unit that tiles space in a crystal.

Rotational symmetry

The symmetries of a crystal structure that remain invariant under certain rotations, such as 3fold or 4fold symmetry.

Lattice type keys

Abbreviations used to describe crystal lattice types: P (primitive), I (body-centered), F (face-centered), C (base-centered).

Surface coordination number

The number of nearest neighbors an atom at the surface of a crystal has, which can differ from bulk coordination numbers.

Cubic interplanar spacing

The distance between parallel planes in a cubic crystal.

Electronegativity

A measure of an atom's ability to attract and hold onto electrons.