1. Chapter 4 Formation of Compounds
4.1 The Variety of Compounds
4.2 How Elements Form Compounds

2. 4.1 The Variety of Compounds

3. Objectives
Distinguish the properties of compounds from those of elements of which they are composed.
Compare and contrast the properties of sodium chloride, water and carbon dioxide.
Analyze evidence to conclude the differences exist in the ways compounds form.

4. Salt: A Familiar Compound
Chemical Name: Sodium Chloride
Formula: NaCl
Very abundant in nature
Large, solid, underground deposits
Dissolved in the oceans
Salt can be obtained by mining the solid deposits or evaporating the seawater

5. Sodium Chloride Uses Food enhancer Essential nutrient in living things
Used to melt ice

6. Physical Properties of NaCl
White solid at room temperature
Crystalline
Brittle
Melting point: 800°C
Dissolves easily in water
Salt water is an excellent conductor of electricity

7. Chemical Properties of NaCl
Does not react readily with other substances.
Does not degrade quickly
No special handling procedures

8. Properties of Sodium Shiny Silvery-white Soft Solid metal
Melting point: 98°C
Stored under oil b/c it reacts with oxygen and water vapor in the air

9. Properties of Sodium One of the most reactive of the common elements
Free element sodium is never found in the environment
Always combined with another element

10. Properties of Chlorine
Pale green
Poisonous gas
Choking odor
Kills living cells
Slightly soluble in water
Excellent disinfectant for water supplies and pools

11. Properties of Chlorine
Nonmetal, halogen
Gas must be cooled to -34°C before it turns to a liquid
Among the most reactive of elements
Handled with extreme care

12. Salt Formation

13. Formation of Sodium Chloride
Two extremely reactive and unstable elements combine to form a stable, safe substance.
+ 

14. Review What are two physical properties of Sodium Chloride?
What is a chemical property of Sodium Chloride?
What are two physical properties of Sodium?
What are two physical properties of Chlorine?

15. 4.1 The Variety of Compounds
(Continued)

16. Carbon Dioxide: A Gas to Exhale
Formula: CO2
Colorless gas
We exhale carbon dioxide as a result of respiration
Plants use carbon dioxide and release oxygen during photosynthesis

17. Physical Properties of CO2
Colorless
Odorless
Tasteless
Gas
When cooled to -80°C, the gas changes directly to a white solid

18. Physical Properties of CO2
Soluble in water
Weak conductor of electricity
“Dry Ice”-does not melt to a liquid

19. Chemical Properties of CO2
Relatively stable
Used in fire extinguishers-does not support burning
Photosynthesis-most significant chemical reaction using CO2.

20. The Properties of Carbon
Nonmetal
Black, brittle solid
Fairly unreactive at room temperature
At higher temps will react with many elements
Burns well: Charcoal is 90% carbon
Forms a huge variety of compounds
Organic chemistry?

21. The Properties of Oxygen
Nonmetal
Colorless
Odorless
Tasteless Gas
21% of the air we breathe
Oxygen supports burning

22. The Properties of Oxygen
Becomes a liquid when cooled to -183°C
Slightly soluble in water
More reactive than carbon
Rusting
Combines with many elements
Most abundant element in Earth’s crust

23. Earth’s Crust

24. Water, Water Everywhere
Formal Chemical name: Dihydrogen monoxide
Formula: H2O
Covers 70% of the Earth
Approx. 70% of the mass of the average human body

25. Physical Properties of Water
Three states: Solid, Liquid, Gas
Boiling Point: 100°C
Freezing Point: 0°C
Pure water does not conduct electricity
Excellent solvent “universal solvent”
Vital in the transport of dissolved materials

26. Water

27. Chemical Properties of Water
Stable
Does not react with many other substances
Medium in which many chemical reactions occur (human body)
Starting material for photosynthesis

28. Properties of Hydrogen
Lightest element
Most abundant element in the universe
Nonmetal
Reactive element
Odorless
Colorless
tasteless

29. Properties of Hydrogen
Seldom found as a free element
React vigorously with many elements, including oxygen forming water
Becomes a liquid at -253°C
Does not conduct electricity
Only slightly soluble in water

30. Using Clues to Make a Case
Elements combine to form compounds with different properties
Elements do not always combine in the same way or all compounds would have similar properties
We will examine how elements combine in the Section 4.2

31. Review What are some properties of Carbon Dioxide?
What are some properties of Oxygen?
What are some properties of Water?
What are some properties of Hydrogen?