1. CHEMISTRY of LIFE
Chapter 2

2. The Nature of Matter

3. Important Terms Atom: basic unit of matter
Fun Fact – 100 million atoms make can fit across your pinkie nail!
Subatomic Particles: make up an atom
Protons – p+
Positively charged particles
Neutrons – n0
neutral particles
Electrons – e-
negatively charged particles
n0 and p+ are found in the nucleus of the atom
e- are found orbiting the nucleus

4. Diagram of an Atom
Yellow = protons
Orange = neutrons
Grey = electrons

5. More Important Terms
Element: a pure substance that consists entirely of one type of atom
All elements are found on the periodic table
Elements are represented by symbols
Ca H Ar I Mg K
Compound: a substance formed by the chemical combination of 2 or more different elements in definite proportions.
Represented by formulas
H2O C6H12O CO2

6. Counting Atoms
Formulas tell us how many of each atom there is in the compound
H2O
How many hydrogens? 2
How many oxygens? 1
C6H12O6
How many carbons? Hydrogen? Oxygen?
6, 12, 6

7. One More Important Term
Molecule: smallest unit of a compound
H2O  only 1 molecule of water
2 H2O  2 molecules of water
CO2  1 molecule of carbon dioxide
5 CO2  5 molecules of carbon dioxide
Let’s count the atoms again.
5 H2O
How many hydrogen?
1 molecule has 2 H but there are 5 molecules
2 x 5 = 10
How many oxygen?
1 x 5 = 5
3 C6H12O6
C = 18, H = 36, O = 18

8. The Periodic Table

9. C 6 Let’s Look at Carbon! Carbon 12.0107 Atomic Number Symbol
Find Carbon on your periodic table! 6
Atomic Number C
Symbol
Carbon
Element Name
Atomic Mass

10. What Does the Periodic Table Tell Us?
Atomic # = # of p+ (You must know this!)
Atomic # never changes!
Atomic Mass tells us the mass of each element.
The protons and neutrons make up the mass!
Mass # = the atomic mass rounded off
Atomic mass of Carbon is so the mass # is 12.

11. How do we figure out n0 and e-?
p+ = e- unless its an ion!
Ion: a positively or negatively charged atom
Cl Na Al S-2
Mass # = p+ + n0
In other words: mass # - p+ = n0
You must know these equations!!!!

12. Let’s Practice! Ex 1: Carbon Ex 2: Aluminum Atomic # = Atomic Mass =6 13 12 27 6 13
12-6 = 6
27-13 =14 6 13

13. Let’s Practice! Ex 3: Gold Ex 4: Barium Atomic # = Atomic Mass =
n0 =
e- =
Ex 4: Barium
Atomic # =
Atomic Mass =
Mass # =
p+ =
n0 =
e- = 79 56
197
137 79 56
= 118
= 81 79 56

14. Chemical Bonds
Ionic Bonds
Covalent Bonds
Hydrogen Bonds

15. Bonding
When looking at bonding between atoms, we are concerned about the number of e- found in the outer orbit of each atom.
We can tell how many e- are in the outer orbit by looking at where the element is located on the periodic table.

16. 1e- in outer shell
8e- (except He – only 2 e)
2e-
3e-
4e-
5e-
6e-
7e-

17. Lewis Dot Diagrams
When drawing out bonds between atoms, we use Lewis Dot Diagrams.
LDDs show the # of e- in the outer orbit by using the symbol surrounded by dots.
Examples:
Sodium is found in the 1st column so it has only 1 e- in outer shell 
Chlorine is found in the 7th column so it has 7 e- in its outer orbit  Na Cl

18. Now you practice! Al N Ar

19. Covalent Bonds
Covalent Bonds occur when e- are shared between 2 atoms.
Goal: to make all atoms “happy”
All atoms want 8 e- in outer shell
One exception = H only wants 2
You can have single (2 e-), double (4 e-), and triple (6 e-) bonds.
Again we will use Lewis Dot Diagrams!

20. Let’s Draw Covalent Bonds
Ex: F2
Ex: H2 F F H H

21. Let’s Draw Covalent Bonds
Ex: N2
Ex: O2 N N O O

22. Let’s Draw Covalent Bonds
Ex: H2O
Ex: NH3 H O H H N H H

23. Ionic Bonds
Ionic bonds occur when e- are transferred from one atom to another
Ions: charged atom due to a loss or gain of e-
Loss of e- results in a positive charge… why?
Gain of e- results in a negative charge… why?
Goal: to make all atoms “happy”
All atoms want 8 e- in outer shell
One exception = H only wants 2
Without a full outer shell, an atom is very “unhappy” or unstable.

24. Ionic Bonds Na Cl Ex: NaCl (Sodium Chloride)
In order for both Na and Cl to be “happy” Na will give its 1 e- to Cl.
How does that make Na “happy”?
Na loses an e- and becomes Na+
Cl gains an e- and becomes Cl- Na Cl

25. Let’s Practice Ionic Bonds!
Ex 1: Cl-
Atomic # =
Atomic Mass =
Mass # =
p+ =
n0 =
e- =
Ex 2: Na+
Atomic # =
Atomic Mass =
Mass # =
p+ =
n0 =
e- = 17 11 35 23 17 11
35-17=18
23-11 =12
17+1=18
11-1=10

26. Now you try! Ex 3: Al+3 Ex 4: S-2 Atomic # = Atomic Mass = Mass # =
p+ =
n0 =
e- =
Ex 4: S-2
Atomic # =
Atomic Mass =
Mass # =
p+ =
n0 =
e- = 13 16
32.066 27 32 13 16
27-13=14
32-16=16
13-3=10
16+2=18

27. Properties of Water

28. Polarity Polarity: the unequal distribution/sharing of e-
Some atoms have a stronger “pull” and therefore hog the e-
Causes an angular shaped molecule

29. Hydrogen Bonding
Due to the partial (+) and (-) charges of H20 molecules, there is an attraction between H20 molecules
(+) hydrogens are attracted to (-) oxygens of other molecules
This causes H-bonds between H and O of different H20 molecules

30. Hydrogen Bonds

31. Cohesion Cohesion: attraction of molecules of the same substance
Cohesion causes surface tension
Allows water to form beads
Allows bugs to “walk” on water

32. Adhesion
Adhesion: attraction of molecules between different substances
Attraction between water and glass forms a meniscus
Allows for capillary action in plants – water can move from the roots all the way to the top of the plant

33. Solutions and Suspensions
Mixtures are composed of 2 or more elements or compounds that are physically combined (not chemically combined)
Salt and pepper, water and oil, sugar and sand
Solution: even distribution of all components in the mixture (salt water, sugar water)
Solute – the substance being dissolved
Solvent – the substance doing the dissolving
Suspension: mixture of nondissolved material in water (oil and water)

34. Solution

35. Suspensions

36. Acids, Bases, and pH

37. Let’s Start with Water H2O H+ + OH- Water is neutral because H+ = OH-
H+ is a hydrogen ion
OH- is a hydroxide ion
Water is neutral because H+ = OH-
When the H+ and OH- are unequal, the result is an acid or a base.

38. The pH Scale (power of hydrogen)
pH scale indicates the concentration of H+ in a solution.
Ranges from 0-14
7 = neutral = pure water
H+ = OH-
Below 7 = Acid
H+ > OH-
Above 7 = Base
H+ < OH-
The lower the pH the greater the acidity.
The higher the pH the greater the basicness.

40. Neutralization Reactions
We can mix an acid and base together in specific proportions to theoretically make water.
When an acid (more H+) is added to base (more OH-), eventually the H+ will balance out the OH-, which makes the substance neutral.

41. Chemical Reactions

42. Chemical Reactions (Chem. Rxn)
Chem rxn: a process that changes one set of chemicals into another
Reactants: compounds that enter into a rxn
Products: compounds that are a result of a rxn
Chem rxn involve changes in bonds
CO2 + H2O  H2CO3
6 CO2 + 6 H2O  C6H12O6 + 6 O2

43. Energy in Rxns Energy is stored in bonds.
Rxns that release energy occur spontaneously.
Energy is released when the bond is broken.
Rxns that absorb energy will only occur with a source of energy
Activation energy: energy required to start a rxn

44. Catalysts and Enzymes
Catalyst: a substance that speeds up the rate of a chem rxn
Lowers activation energy
Enzyme: protein that acts as a biological catalyst
Speeds up rxns in cells
Enzymes are very specific to the process it has to speed up.

46. Organic Molecules
Carbohydrates
Lipids
Proteins
Nucleic Acids

47. Carbohydrates Sugar Elements: Carbon, hydrogen, oxygen
Monomers: Monosaccharides
Glucose, fructose, lactose
2:1 ratio of Hydrogen:Oxygen
Job:
Main source of energy for all living things (from the break down of sugars)

48. Glucose

49. Lipids Fats and Oils Elements: carbon, hydrogen, oxygen
Monomers: 1 glycerol, 3 fatty acids
H:O ratio is much greater than 2:1
Jobs:
Long term energy storage
Make up cell membranes
Waterproof covering on leaves

51. Proteins Elements: carbon, hydrogen, oxygen, nitrogen
Monomers: Amino Acids (there are 20)
Functional Groups:
Amino group = NH2
Carboxyl group = COOH
“R” group
Jobs:
Speeds up chemical reactions
Pumps molecules in and out of the cell
Cell movement (cilia and flagella)

52. Alanine
Serine

53. Nucleic Acids DNA and RNA
Elements: Carbon, Hydrogen, Oxygen, Nitrogen, and phosphorus
Monomers: Nucleotides
Adenine, Thymine, Cytosine, Guanine, Uracil
Functional groups:
Phosphate group
Nitrogenous base
5 carbon sugar (either deoxyribose or ribose)
Job:
Carries genetic information