Solids & Liquids
• I. IMF – intermolecular forces -Attractive forces between molecules.– A. Much weaker than chemical bonds within molecules.
• London forces & Dipole-Dipole forces: View animation online.
• Hydrogen bonds
• II. Liquids – fluid (ability to flow) definite volume, takes the shape of its container– A. Properties & kinetic molecular
theory – molecules in constant random motion, much less KE than gases & molecules are closer together
• 1. density – d = mass/vol compared to gases density is much greater
• 2. incompressibility – much less commpressible than gases
• 3. ability to diffuse – can diffuse but not as fast as gases because liquid molecules are closer together & the IMF are much greater
• 4. surface tension – force that pulls adjacent particles at the surface of a liquid together – causes liquids to “bead”– a. water has a much higher surface tension than
most other liquids
And 1 more!
• water strider
• A tiny water walking
machine/robot
Image Credit: Environmental Graffiti
• b. capillary action – attraction of a surface of a liquid to the surface of a solid – causes meniscus
• water mercury (surface tension stronger than
capillary action)
• 5. evaporation – particles escaping from the surface of a non-boiling liquid into gas state– a. vaporization – phase change of liquid to gas or
solid to gas phase change• 6. boiling – change liquid to gas by adding heat
E – change happens through out liquid not just at the surface
• liquid + heat gas (endothermic)
• 7. freezing – phase change of liquid to solid by removing heat E
• Liquid solid + heat (exothermic)
III. Solids- definite shape & volume
• A. Properties & kinetic molecular theory-(IMF stronger) molecules are in a fixed,
vibrating position – 1. definite shape & vol
• a. crystalline solids – made of crystals• 1) crystal – particles arranged in an
orderly, repeating, geometric pattern
• b. amorphous solid – particles are arranged randomly
• 2. Definite melting point – temp at which a solid becomes liquid
– a. melting – physical change from solid to liquid solid + heat→ liquid (endothermic)– b. supercooled liquids – substances that retain
certain liquid properties even when at a temp where they appear solid --- glass, plastics
• 3. Density & incompressibility – more dense than gases & liquids, least comp.
• D = mass ÷ volume
• 4. Diffusion – can occur but at an incredibly slooooow rate (for practical purposes we can say that it doesn’t diffuse
B. Crystalline Solids
• 1. crystal structure- 3-D arrangement of particles in a crystal
• 2. unit cell – smallest part of a crystal that shows the 3-D arrangement of the crystal
• 3. binding forces in crystals– a. covalent network – made of single atoms,
each are covalently bonded to its nearest neighbor, hard, brittle, nonconductor or semiconductor (diamond, quartz, graphite)
• b. metallic crystal – metal atoms surrounded by a sea of electrons,good conductor, malleable….
• . ionic crystals – made of + & - ions arranged in a regular pattern, hard, brittle, ↑mp, good insulator
• d. covalent molecule – covalently bonded molecules held together by IMF, ↓ mp, soft, good insulator, easily vaporized, polar cov. more strongly held together than nonpolar cov.
• covalent network • Metallic decreasing• m.p. melting point• ionic • polar covalent• covalent molecular