2. Paper XII (IVSemester)
Presentation ON
CRYSTAL STRUCTURE
Paper XII (IVSemester) By
Dr. Kshirsagar S.V.

3. Ionic solids Molecular Solids Covalent Solids Metallic solids
STRUCTURES OF CRYSTALLINE SOLID TYPES
Molecular Solids
Covalent Solids
Ionic solids
Metallic solids
Na+
Cl-

4. QUARTZ
DIAMOND
GRAPHITE

5. CRYSTAL STRUCTURE
Crystal structure is the periodic arrangement of atoms in the crystal. Association of each lattice point with a group of atoms(Basis or Motif).
Lattice: Infinite array of points in space, in which each point has identical surroundings to all others.
Space Lattice  Arrangements of atoms
= Lattice of points onto which the atoms are hung.
Space Lattice + Basis = Crystal Structure =
• • • +
Elemental solids (Argon): Basis = single atom.
Polyatomic Elements: Basis = two or four atoms.
Complex organic compounds: Basis = thousands of atoms.

6. a a ONE DIMENTIONAL LATTICE ONE DIMENTIONAL UNIT CELL a
UNIT CELL : Building block, repeats in a regular way a a

7. TWO DIMENTIONAL LATTICE

8. TWO DIMENTIONAL UNIT CELL TYPESb
a  b,   90°
a  b,  = 90°
a = b,  = 90°
a = b,  =120°

9. EXAMPLE OF TWO DIMENTIONAL UNIT CELL

10. TWO DIMENTIONAL UNIT CELL POSSIBILITIES OF NaCl

11. THREE DIMENTIONAL UNIT CELLS / UNIT CELL SHAPES1 7 2 3 4 5 6

12. LATTICE TYPES
Primitive ( P )
Body Centered ( I )
Face Centered ( F )
C-Centered (C )

13. BRAVAIS LATTICES
7 UNIT CELL TYPES + 4 LATTICE TYPES = 14 BRAVAIS LATTICES

14. Thank You