1. Chapter 2: The Chemistry of Biology

2. The Composition of the Universe
A. Element: a pure substance that cannot be broken down chemically into other kinds of matter.
1. Ex: Oxygen, Carbon, Hydrogen, Nitrogen, Phosphorus

3. The Composition of the Universe
B. Atom: simplest part of an element
C. Subatomic Particles: Parts of an atom
1. Protons: positively (+) charged particles
a. Found in the nucleus of an atom
2. Neutrons: neutral particles

4. The Composition of the Universe
3. Electrons: negatively charged particles
a. Found moving around the nucleus in energy levels
b. Valence electrons – electrons in the last shell or energy level of an atom
** Hint: ** The number of valence electrons for an atom, is determined by the column (group) number it falls under on the Periodic Table of Elements. For example, an atom in the 3rd column, have 3 valence electrons.

5. The Composition of the Universe
The Electron Energy Levels
Bohr Model of Carbon:

6. The Composition of the Universe
Lewis Dot Structure:

7. The Composition of the Universe
D. How do you determine the number of protons?
1. Equal to the atomic number
E. How do you determine the number of electrons?
1. Equal to the # of protons (atomic number) in a stable atom
F. How do you determine the number of neutrons?
1. Equal to the Atomic Mass (rounded) – Atomic #

8. The Composition of the Universe
The Electron Energy Levels
Bohr Model of Carbon:

10. Bonding
A. All atoms “want” to be stable; if they do not have 8 valence electrons in their outer most shell, then they tend to undergo reactions to find stability 1. BONDS are then formed!

11. Occurs or Found Between?
Bonding
Type of Bond
Occurs or Found Between?
How is the bond formed?
Additional Info
Ionic
Metals and Non-metals
Electrons are transferred between atoms
Ion: positive & negatively charged atoms formed (Na+, Cl-)

12. Bonding
Is it easier for Potassium to gain or lose electrons to have a stable outermost ring of electrons?

13. Bonding
What about Chlorine?

14. The Composition of the Universe
Ionic Bonding Results

15. The Composition of the Universe

16. Occurs or Found Between?
Bonding
Type of Bond
Occurs or Found Between?
How is the bond formed?
Additional Info
Covalent
2 or more Non-metals
Electrons are shared between atoms
Can be polar or non-polar bonds depending on electron sharing

17. Occurs or Found Between?
Bonding
Type of Bond
Occurs or Found Between?
How is the bond formed?
Additional Info
Van der waals forces
Between molecules
(intermolecular)
Oppositely charged areas of molecules are attracted to each other
Very weak bonds; allows geckos to walk upside down; found between water molecules + -
ATTRACTION OF DIFFERENT CHARGES BETWEEN MOLECULES

18. Bonding
Ex: Gecko Foot – has half a million hair like projections that are divided into fibers
Forces form between the hairs on the feet and surface allowing the gecko to balance gravity

19. Building More Complex Substances
B. Building More Complex Substances
1. Compound: substance formed by the chemical combination of atoms from two or more elements
a. Ex: H2O (water), C6H12O6 (glucose), CO2 (carbon dioxide)
The properties of the compound are different than those of the elements that create it!

20. Building More Complex Substances
B. Molecule: the simplest form of a compound; when two or more atoms join
1. Ex: O2 (oxygen gas), H2O (water)
*All compounds are molecules, but not all molecules are compounds**

21. Mixing It Up…Solutions!
A. Solution: a mixture in which one or more substances are uniformly distributed in another substance.
1. Two major components a. Solute: substance dissolved into the solution
b. Solvent: substance in which the solute is dissolved
Ex: WATER IS THE UNIVERSAL SOLVENT

22. Mixing It Up…Solutions!
B. How do we analyze the strength of a solution? Concentration (amount of solute dissolved in solution)
10g g g g g
100mL mL mL mL mL

23. pH Scale
A. pH Scale: measures the concentration of hydrogen (H+) ions and hydroxide ions (OH-) in solution
Range of the Scale: 0-14

24. pH Acid: Range: 0-7 H+ Ions: [High] OH – Ions: [Low]
Ex: HCl (stomach acid), milk

25. pH Base: Range: 7-14 H+ ions: [Low] OH- ions: [High]
Ex: Blood, Ammonia, Sea Water

26. pH Neutral: Range: 7 H+ ions: [Equal] OH- ions: [Equal] Ex: WATER!
What are the strong acids?
What are the strongest bases?

27. The Chemistry of Water
A. COVALENT bonds: join hydrogen and oxygen that make up water
1. Electrons are not shared EQUALLY!
a. Oxygen has electrons
b. Hydrogen only has 1 electron
The oxygen atom pulls the shared electrons towards its own nucleus and away from the hydrogen.

29. The Chemistry of Water
B. Polarity: the distribution of charges in atoms joined by a bond
1. Polar compound: a molecule with an uneven pattern of charge or unequal sharing of electrons
a. Ex: Water, Sugars, Proteins, DNA (good at dissolving things!)
2. Non-polar compound: a molecule with an even pattern of charge or equal sharing of electrons
a. Ex: Oxygen gas, fats, waxes + + -

30. Polarity of Water C. Polarity of WATER
1. Causes water molecules to attract to each other or be “sticky” and form van der waals forces between them
a. Hydrogen Bond: attraction holding two+ water molecules together
Positive (H+) region of one water molecule is attracted to the negative (O-) region of another
These are weak bonds; they can be broken easily!

31. Why is hydrogen bonding important to life and biology?
A. Creates cohesion of particles
1. Attractive forces between particles of the same type
a. Ex: Water “sticks” allowing striders to move across; Floating a paperclip on water

32. Polarity of Water
Surface Tension: created by cohesion; a force existing on the surface of a liquid, preventing the layer from being broken

33. Why is hydrogen bonding important to life and biology?
B. Creates adhesion of particles
1. Attractive forces between different/unlike substances
a. Ex: meniscus on a test tube

34. Why is hydrogen bonding important to life and biology?
C. Capillary Action: water molecules move upward through narrow tubes against the force of gravity because of cohesion and adhesion
1. Ex: flower, redwood tree

35. Why is hydrogen bonding important to life and biology?
D. High Specific Heat Capacity & Heat of Vaporization:
1. Water must gain or lose large amounts of energy (heat) to break the hydrogen bonds for any temperature change or evaporation to occur.
a. Why is this important?
Helps organisms maintain homeostasis
Helps moderate climate/ocean water temperature

36. Why is hydrogen bonding important to life and biology?
E. Water EXPANDS becomes LESS dense when it freezes!
1. Why is this significant?
a. Ice floats preventing the water from freezing solid and insulates the lower layers, allowing life to survive underneath it

37. Why is hydrogen bonding important to life and biology?
F. Water is the universal solvent.
1. Water dissolves more solutes than any other liquid.

38. Penny Lab Video