1. The Structure of Matter
Compounds and Molecules

2. What are Compounds?
Compounds are 2 or more elements chemically bonded together

3. Mixtures Physical Blend of two or more pure substances
Elements and compounds

4. Examples of Molecular Substances
Many examples

5. Compounds Chemical Bonds are forces that hold compounds together
A compound always has the same chemical formula
H2O
NaCl
KNO3
CO2

6. Reading Chemical Formulas
Chemical formulas tell us a lot.
The subscripts tell us how many atoms or ions are in the compound
A compound always has the same chemical formula
H2O
NaCl
KNO3
CO2
HCl

7. Chemical Structure-shows how compounds atoms or ions are connected Positions of Atoms 1) Bond Length- is the distance between nucleus 2) Bond Angle- is the orientation in space

8. Models of Compounds Ball and Stick model Structural Formula
shows structures, how they are built.
H O H
Space Filling Models shows the space filled up by the atoms

9. How does Structure affect Properties?
States (solids, liquids, gases)
Melting points
Boiling points
Freezing Points

10. Network Structures
Arrangement of ions or atoms continues throughout the substance
More rigid
Strong solids
Bonded ions
Metal and a non-metal bonded
Example Sodium Chloride (NaCl), salt

11. Molecules Sugar C6H22 O11 Some compounds are made of molecules
Two non-metals bonded together
Structures vary
Not as strongly bonded

12. Network vs. Molecules Network Solids Molecules Properties Properties
Compound
25C
Melting Pt.(C)
Boiling Pt. (C)
Silicon
Dioxide
Solid
1700
2230
Magnesium Fluoride
1261
239
Sodium
Chloride
801
1413
Compound
25C
Melting Pt.(C)
Boiling Pt. (C)
Sugar
Solid
Water
Liquid
100
Hydrogen sulfide
Gas
-86
-61

13. Special Water Attractions
Attractions between water molecules are called hydrogen bonds
Not as strong as the bonds between hydrogen and oxygen atoms in the water molecule itself