Covalent crystal

This is a presentation about the covalent crystal structure prepared by me,
Covalent crystals are solids in which the lattice points are occupied by atoms that are covalently bonded to other atoms at neighbouring lattice sites. ... These solids are sometimes called network solids because of the interlocking network of covalent bonds extending throughout the crystal in all directions.

1. Covalent crystal A covalent crystal is a solid that consists of atoms held together in large networks or chains by covalent bonds. Diamond Graphite

2. Properties of covalent crystals High melting points Hard and rigid Giant covalent network structure Quartz

3. Properties of covalent crystals Bad conductors of electricity (except graphite) High latent heat of fusion Low co efficient of expansion Silicon carbide

4. Diamond Diamond  is a solid form of the element carbon with its atoms arranged in a crystal structure called  diamond  cubic. 

5. Structure of diamond Diamond  has a giant covalent  structure  in which: each carbon atom is joined to four other carbon atoms by covalent bonds. The carbon atoms have a regular lattice arrangement. there are no free electrons.

6. Structure of diamond

7. Graphite Graphite  is a naturally-occurring form of crystalline carbon. Graphite  is a mineral of extremes. It is extremely soft, cleaves with very light pressure, and has a very low specific gravity.

8. Structure of graphite Each carbon atom is joined to three other carbon atoms by covalent bonds Each carbon atom has one non-bonded outer electron, which becomes  delocalised

9. Structure of graphite

10. Metallic crystals Metallic crystals are held together by metallic bonds, electrostatic interactions between cations and delocalized electrons.

11. Properties of metallic crystal Good conductor of heat and electricity Lustrous(shiny) Generally known as sea of electrons. Malleable and ductile(atoms can slide over each other).

12. Examples of metallic crystals