Class 12 Chemistry: Chapter 1 - The Solid State

Vocabulary flashcards covering core definitions, particle contributions, coordination numbers, relations, and formulas for Class 12 Chemistry Chapter 1 (The Solid State).

Solid

A substance with definite shape and definite volume.

Crystalline solids

Solids with a regular, repeating arrangement of particles.

Amorphous solids

Solids with an irregular arrangement of particles.

Anisotropy

Different physical properties in different directions.

Isotropy

Same physical properties in all directions.

Unit cell

The smallest repeating unit of a crystal lattice.

Types of cubic unit cells

Three: simple cubic, body-centred and face-centred.

Coordination number of BCC

$$8$$

Coordination number of FCC

$$12$$

Packing efficiency of FCC

$$74\%$$

Number of particles in a simple cubic unit cell

$1$ particle

Number of particles in a BCC unit cell

$2$ particles

Number of particles in an FCC unit cell

$4$ particles

Contribution of a corner atom

$$\frac{1}{8}$$

Contribution of a face-centred atom

$$\frac{1}{2}$$

Contribution of a body-centred atom

$1$ whole atom

Relation between edge length ($a$) and radius ($r$) in SC

$$a = 2r$$

Relation between edge length ($a$) and radius ($r$) in BCC

$$\sqrt{3}a = 4r$$

Relation between edge length ($a$) and radius ($r$) in FCC

$$\sqrt{2}a = 4r$$

Formula for density of a unit cell

$$\rho = \frac{ZM}{a^3 \times N_A}$$