1. TOPIC 3 THE CHEMICAL BASIS OF LIFE

2. How many elements are found on earth?
How many of them are found in human body?
How do we get them?
How do plants get them?
Why do we get them?
Do we need these elements in equal amounts?

3. Chemical composition of living organisms

5. Trace elements

6. Revision of basic chemistry
What is an element?
What is an atom?
Atomic structure?
What is a molecule?
What is a compound?
What is an ion? (polyatomic ions)

7. Elements and compounds

8. Atomic structure

9. Electron arrangement

10. Why do atoms bind with each other?
To make their outer shells complete so they resemble noble gases
What happens as a result?
Energy is stored and released
Various chemical structures are formed
What causes atoms to make bonds?
Electronegativity

11. Inorganic and organic molecules
Inorganic molecules: are the molecules which do not contain carbon. (CO2, HCO3- and carbonate are exceptions)
Organic compounds: are the molecules which contain carbon. There are more than different compounds.
Living things have both inorganic and organic compounds.

12. Intramolecular bonds a) Ionic bonding

14. Intramolecular bonds b) Covalent bonding
Nonpolar covalent bonds
Polar covalent bonds

16. Draw a water molecule.
Draw three water molecules that are bonded together.
Name the bond within the water molecule.
Name the bond between the water molecules.
Are water molecules polar or nonpolar?
What is the reason of the bonding between water molecules?

17. Polarity

18. Hydrogen bonding

19. What is the importance of polarity of water for living things?

20. 1- Solvent of life Do all molecules dissolve in water?
Importance for living things?

22. 2. Cohesion and adhesion

24. Capillary
action

25. Which one will feel hotter?
You want to have pasta for dinner so you start boiling some water in a pot. After a few minutes you touch the pot and the water inside.
Which one will feel hotter?

26. Why does the sand burn your feet?
You are at the beach just out from the sea, walking on sand. The sand burns your feet. This puzzles you since the sea was quite refreshing.
Why does the sand burn your feet?

27. Why hasn’t the ice melted?
It’s been snowing during the last week. You realize that the ice on the sidewalk still hasn’t melted although last few days have been quite sunny and warm.
Why hasn’t the ice melted?

28. Specific heat capacity ability to absorb heat energy
The quantity of heat per unit of mass required to raise the temperature by 1 degrees Celcius OR
ability to absorb heat energy
Does a substance that heats up quickly have high or low specific heat capacity?

29. temp. increase by 1g of water 10C 1g of iron
X amount of of heat 1g of alcohol
1g of iron

30. Heat of vaporization
The amount of thermal energy needed to change a substance from liquid to gas or gas to liquid
Heat of fusion
The amount of thermal energy needed to change a substance from liquid to solid or solid to liquid

31. 3. Temperature moderation

33. Why do lakes freeze on top?

34. 4. Density of ice

36. Which one is ice, which one is water?

37. What are the functions of water in the living things?
Temperature moderation
Solvent
Cohesion
Habitat
Chemical reactions (photosynthesis, digestion ……)

38. ACID AND BASES

39. Acids: Release H+ in aqueous solutions HCl H+ + Cl-

40. Bases: Release OH+ OR Accept H+ in aqueous solutions NaOH Na+ + OH-

41. Buffers: Solutions that stabilize pH changes. How
Buffers: Solutions that stabilize pH changes. How? Release H+ when the solution becomes too basic OR Accept H+ when the solution becomes too acidic

42. Bicarbonate buffer in blood
H2O + CO H2CO HCO3 + H+