1. Properties of Compounds

2. Properties of Ionic Compounds
Usually Crystalline Solids at Room Temperature
Fluorite - CaF2
Barite – BaSO4
Wulfenite - PbMoO4

3. Properties of Ionic Compounds
Each ion is strongly attracted to each of it’s neighbors
These strong attractive forces result in a very stable structure
This is reflected in the fact that ionic compounds generally have high melting points
Going from a solid to a liquid (melting) requires adding enough energy to the atoms, ions, or molecules to overcome the attractive forces holding them together in a solid.

4. Properties of Ionic Compounds
Melting point of some ionic compounds:
Sodium chloride = 801C (1474F)
Fluorite = 1403C
Barite = 1508C
Wulfenite = 1065C

5. Properties of Ionic Compounds
Usually high solubility in water
An electrolyte is a compound that conducts an electric current when it is dissolved in water or melted
All ionic compounds are electrolytes
Electrolyte demo!

6. Properties of Metals Metals are good conductors of electricity
Metals are ductile – able to be drawn into wires
Metals are malleable – able to be hammered or forced into shapes
Ductility and malleability can both be explained by the “sea of electrons” model –
When metals are subjected to pressure, metal cations easily slide past each other like ball bearings in oil.
By contrast, if an ionic crystal is struck with a hammer, the hit pushes positive ions closer together , they repel each other, and the crystal breaks.

7. Properties of Metals
Alloys – mixtures of 2 or more elements where at least one is a metal
Alloys have properties that are superior to those of component elements
Sterling silver is an alloy that is 92.5% silver and 7.5% copper
Sterling silver is harder and more durable than pure silver
Steels are important alloys today
Steels contain a number of different elements
(Fe, C, B, Cr, Mn, Mo, Ni, W, V)
Steels are corrosion resistant, ductile, hard, and tough

8. Properties of Molecular Compounds
Molecular compounds tend to have lower melting points and boiling points than ionic compounds
Many molecular compounds are gases or liquids at room temperature
Solids are often brittle
Poor to non-conductor of electricity when dissolved in water
Anywhere from high to low solubility in water

9. Properties of Network Covalent Compounds
Melting a network covalent solid would require breaking covalent bonds throughout the solid
Diamond, a network covalent solid, does not melt. Instead it vaporizes to a gas at 3500C
Silicon carbide, another network covalent solid, melts at 2700C