[2] Crystalline Solids - Classification based on Forces of Attraction and Symmetry

ionic crystals

Ionic bond

a. Ionic

b. Covalent

c. Molecular

d. Metallic

atomic/covalent crystals

covalent bond

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Molecular crystals

Van der Waals

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystals

Metallic bond

a. Ionic

b. Covalent

c. Molecular

d. Metallic

-ionic crystals

-atomic/covalent crystals

Hard, brittle

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Molecular crystals

Soft

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystals

Hard/soft

a. Ionic

b. Covalent

c. Molecular

d. Metallic

lattice defects

The hardness or softness of metallic crystals is based on the ______ defects

imperfections

lattice defects are

soft

if high lattice defects

hard

if low lattice defects

-ionic crystals

-atomic/crystals

High MP

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Molecular crystals

Low MP

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystals

High/Low MP

a. Ionic

b. Covalent

c. Molecular

d. Metallic

-Ionic crystals

-Atomic crystals

-Molecular crystals

Poor conductor of heat and electricity

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystals

Good conductor of heat and electricity

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Ionic crystal

NaCl

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Covalent/Atomic crystal

diamond

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Molecular crystal

Argon

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystal

Sodium (Na)

a. Ionic

b. Covalent

c. Molecular

d. Metallic

Metallic crystal

Mg

Molecular crystal

Solid CO2 (dry ice)

atomic crystal

graphite

Ionic crystal

LiF

ionic crystal

MgO

atomic

quartz (SiO2)

Molecular

I2

Molecular crystal

H2O

Metallic crystal

Fe

Ionic crystal

CaCO3

Molecular crystal

Sucrose

Metallic crystal

Cu

Molecular crystal

Naphthalene

Ionic crystal

CaF

Metallic crystal

Ni

metallic crystal

All metallic elements

ionic crystals

Salts are

geometric shapes

Classification based on the symmetry

X-ray diffraction studies

Virtually all that is known about the crystal structure has been learned from

X-ray diffraction

refers to the scattering of X-rays by the units of a crystalline solid

Unit Cell

The basic repeating structural unit of a crystalline solid

Cubic

Sodium chloride symmetry/geometric shape

Tetragonal

Urea symmetry/geometric shape

Orthorhombic

Ritonavir II symmetry/geometric shape

Monoclinic

Sucrose symmetry/geometric shape

Monoclinic

Ritonavir I symmetry/geometric shape

Triclinic

Boric acid symmetry/geometric shape

Rhombic/Rhombohedral

Iodine symmetry/geometric shape

Hexagonal

Iodoform symmetry/geometric shape

sodium chloride

highest symmetry

Boric acid

lowest symmetry