Chapter 10 States of Matter 10.3 The nature of solids

Things you will learn You will understand that the degree of organization of particles is the difference between solids and either gases or liquids You will know the meaning of crystal lattice and how that determines the crystal shape

Things we might know about solids Denser than both gases and liquids (usually) Non-compressible Does not flow (resists shear) Does not fill a container completely

Model for solids While particles in liquids and solids are able to move along and past one another, those in solids cannot Particles in solids vibrate in place and are closer together than those in liquids

Heating and melting solids When heated to a high enough temperature, the particles in a solid vibrate enough that the structure of the solid breaks down and melts

Melting and freezing Melting and freezing points of materials are the same. They are the equilibrium point when both phases can exist. Ionic substances (metal and non-metal) have high melting temperatures because of strong forces holding them together Molecular substances have much lower melting temperatures due to weak intermolecular forces

Strong ionic bond

Strong covalent bond

Weak intermolecular bond

Water ice melting

Crystal structure Most solids are crystalline The particles are lined up in an orderly way called a crystal lattice Crystals have a regular shape with faces characteristic of that substance

Unit cells the smallest group of particles which keeps the shape of the crystal

Allotropes

Amorphous substances

Amorphous rocks and crystalline rocks

Sim 2