The Nature of Solids Chapter 10

Solids: Gases = very free to move Liquids = relatively free to move Solids = not very free to move

Solids: Solids do not move freely like liquids and gases Rather, they vibrate about fixed points

Solids: Do not take the shape or volume of the container They are dense and incompressible

Solids and kinetic energy: Increase in average kinetic energy = increase in particle vibration = increase in temperature

Melting Point: Mp = Solid turning to liquid Vibrations are strong enough to overcome the intermolecular interactions

Freezing Point: Opposite of melting point Liquid turns into a solid because the particles slow down and intermolecular forces are stronger

Equilibrium: A solid will melt and freeze at the same temperature This is the point of equilibrium, assuming temperature is remaining constant

Solids: Ionic Solids (ex: NaCl) = high melting points They have relatively strong forces holding them together

This is table salt

Solids: Molecular compounds = low melting temperatures Example – hydrogen chloride has a melting temperature of C

Solids: Not all solids melt, some will decompose Example: wood, cane sugar

Sugar or Rock Candy MMMMMM

Crystal structure: Crystalline (crystals) = atoms, ions or molecules are arranged in a repeated, three dimensional pattern called a crystal lattice

Crystals:

Diamond Structure

Crystals: Have regular shape Shape reflects the arrangement of the particles within the solid Types of bonds determines the melting point Ionic = high melting point Molecular = low melting point

Graphite Structure

Crystals: Have sides or faces Angles of the sides for a given crystal are always the same

Crystal Classification: Galena –Cubic

Crystal Classification: Zircon –Tetragonal

Crystal Classification: Blue Topaz –Orthorhombic

Crystal Classification: Gypsum –Monoclinic

Crystal Classification: Amazonite –Triclinic

Crystal Classification: Tourmaline –Hexagonal

Crystal Classification: Calcite –Rhombohedral

Shape of Crystals: Shape depends on arrangement of crystals Unit cell = smallest group of particles that retains geometric shape

More than one Form? Carbon is an example of a crystal that can exist in more than one form

Many forms of carbon: Diamonds Graphite Buckyball or Buckminsterfullerene carbon atoms shaped like a soccer ball

Many forms of Carbon: Allotropes –Two or more molecular forms of the same element in the same physical state (diamond, graphite & buckyballs)

Example: diamonds and graphite

Amorphous Solids: Lack ordered internal structure Non- crystalline Example- rubber, plastics, asphalt and glasses –Glasses are sometimes called super cooled liquids

Nature of Liquids Now, go on to the Nature of Liquids Power Point Click Here Click Here to go to go to Nature of Liquids Nature of Liquids