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