1. Chapter 2
Matter
and
Energy

2. Matter and Energy Matter—anything that occupies space and has mass
Energy—the ability to do work
(for biologists, it includes-)
Chemical energy
Mechanical energy
Heat

3. All matter is composed of atoms
About 120 elements, 91 occur naturally
96% of the body is made from four elements
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
CHON

4. All matter is composed of atoms
Other elements in the body include:
Ca, P, K, S, Na, Cl, Mg, I, Fe
Trace elements include: Cr, Cu, Co, F, Mn and others
CHON

5. Atomic Structure – Subatomic particles
Name Symbol Mass Charge Location
Proton
Neutron
Electron
Figure 2.1

6. Atomic Structure – Subatomic particles
Name Symbol Mass Charge Location
Proton p amu in nucleus
Neutron n amu in nucleus
Electron e amu
around nucleus, in electron cloud
Figure 2.1

7. Atomic Structure
Figure 2.1

8. Atomic Structure of Smallest Atoms
Electrons have different energy levels. Only the outer level affects an atom’s chemical properties!
Figure 2.2

9. K 19 Atomic number —equal to the number of protons
Identifying Elements
Atomic number —equal to the number of protons
Atomic mass number —sum of the protons and neutrons 19
Atomic Number = number of protons K
Average atomic mass, in amu/atom
Name
Symbol
Potassium

10. K 20 17 Identifying Elements Sulfur Name Symbol AtomicNumber
Atomic Mass Number
# p
# n
(most likely)
# e-
Sulfur K 20 17

11. S 16 32 K 19 39 20 Ca 40 Cl 17 35 18 Identifying Elements Sulfur
Name
Symbol
AtomicNumber
Atomic Mass Number
# p
# n
(most likely)
# e-
Sulfur S 16 32
Potassium K 19 39 20
Calcium Ca 40
Chlorine Cl 17 35 18

12. Isotopes and Mass Number
Have the same number of protons
Vary in number of neutrons
Figure 2.3

13. Isotopes and Mass Number
Chlorine has two common isotopes,
Cl-35 and Cl-37
Figure 2.3

14. Isotopes and Mass Number
Chlorine has two common isotopes,
Cl-35 and Cl-37
How many neutrons in each?
Figure 2.3

15. Isotopes and Mass Number
Chlorine has two common isotopes,
Cl-35 and Cl-37
How many neutrons in each?
How many protons in each?
Figure 2.3

16. Isotopes and Mass Number
Chlorine has two common isotopes,
Cl-35 and Cl-37
How many neutrons in each?
How many protons in each?
Which one is more common?
Figure 2.3

17. Isotopes and Mass Number
Chlorine has two common isotopes,
Cl-35 and Cl-37
How many neutrons in each? 18 and 20
How many protons in each? 17
Which one is more common? Cl-35
Figure 2.3

18. Isotopes and Average Atomic Mass
Usually closest to mass number of most abundant isotope
Average atomic mass reflects natural isotope variation
Take the average atomic mass and round to the nearest whole number for the mass number of the most common isotope

19. Isotopes and Average Atomic Mass
The periodic table is arranged by atomic number.
The average atomic mass usually increases with atomic number.

20. Isotopes and Average Atomic Mass
The periodic table is arranged by atomic number.
The average atomic mass usually increases with atomic number.
Find 3 exceptions.

21. Isotopes and Average Atomic Mass
The periodic table is arranged by atomic number.
The average atomic mass usually increases with atomic number.
Find 3 exceptions.
Why does this (rarely) occur?

22. Isotopes and Average Atomic Mass
The periodic table is arranged by atomic number.
The average atomic mass usually increases with atomic number.
Find 3 exceptions.
Why does this (rarely) occur?

23. Radioactivity—process of spontaneous atomic decay
Radioisotopes are radioactive
Typically an unusually heavy isotope
Tend to be unstable
Decompose to more stable isotope
Used in medical diagnosis and treatment

24. Compounds
Elements combine to form compounds.
Figure 2.4

25. Chemical Reactions
Atoms are joined by chemical bonds (ionic or covalent)
A chemical reaction forms and/or breaks chemical bonds

26. Electrons and Bonding Electrons occupy energy levels
Each level has distinct properties
The number of electrons has an upper limit
Levels closest to the nucleus fill first

27. Electrons and Bonding
Bonding involves electrons in the outer level (the valence shell)
The ROW on the periodic chart indicates the valence level
Full valence shells do not form bonds

28. Bonding leads to stability
Atoms are stable when the outermost level is complete
How to fill the energy levels
Level 1: maximum of 2 electrons
Level 2: maximum of 8 electrons
Level 3: maximum of 18 electrons
The valence shell can hold a maximum of 8 electrons
The COLUMN on the periodic chart indicates the number of valence electrons in an atom

29. Atoms will gain, lose, or share electrons to complete their valence shells and reach a stable state
Octet Rule – the Rule of eights
Atoms are considered stable when their valence shell has 8 electrons
(Except for level 1, Hydrogen: use the duet rule)

30. Inert Elements
Figure 2.5a

31. Reactive Elements Valence shells are not full and are unstable
Tend to gain, lose, or share electrons
These elements form chemical bonds!
Figure 2.5b

32. Chemical Bonds Ionic bonds
Form when electrons are transferred from one atom to another
Ions
Charged particles—protons don’t equal electrons
Cations are positive (have lost e-)
Anions are negative (have gained e-)

33. Nonmetals gain (or share) electrons
Chemical Bonds
Ionic bonds
Form when electrons are transferred from one atom to another
Ions
Charged particles—protons don’t equal electrons
Cations are positive (have lost e-)
Anions are negative (have gained e-)
Metals lose electrons
Nonmetals gain (or share) electrons

34. Na+ 9 12 Identifying Ions Iodide ion Name Symbol AtomicNumber
Atomic Mass Number
# p
# n
(most likely)
# e-
Iodide
ion
Na+ 9 12

35. I- 53 127 74 54 Na+ 11 23 12 10 F- 9 19 Mg+2 24 Identifying Ions
Name
Symbol
AtomicNumber
Atomic Mass Number
# p
# n
(most likely)
# e-
Iodide
ion I- 53
127 74 54
Sodium ion
Na+ 11 23 12 10
Fluoride F- 9 19
Magnesium ion
Mg+2 24

36. Ionic Bonds Na Cl Sodium atom (Na) (11p+; 12n0; 11e–)
Chlorine atom (Cl) (17p+; 18n0; 17e–)
Figure 2.6, step 1

37. Ionic Bonds Na Cl Sodium atom (Na) (11p+; 12n0; 11e–)
Chlorine atom (Cl) (17p+; 18n0; 17e–)
Figure 2.6, step 2

38. + – Ionic Bonds Na Cl Na Cl Sodium atom (Na) (11p+; 12n0; 11e–)
Chlorine atom (Cl) (17p+; 18n0; 17e–)
Sodium ion (Na+)
Chloride ion (Cl–)
Sodium chloride (NaCl)
Figure 2.6, step 3

39. Chemical Bonds Covalent bonds
Atoms become stable through shared electrons
Single covalent bonds share one pair of electrons
Double covalent bonds share two pairs of electrons

40. Examples of Covalent Bonds
Figure 2.7a

41. Examples of Covalent Bonds
Figure 2.7b

42. Examples of Covalent Bonds
Figure 2.7c

43. Valence Rules
In general: Carbon makes 4 bonds Hydrogen makes 1 bond Oxygen makes 2 bonds Nitrogen makes 3 bonds
Figure 2.7c

44. Polarity —the most important chemical property
Figure 2.8

45. Polarity —the most important chemical property
Some molecules are non-polar
Some are polar
Have a positive and negative side
Figure 2.8

46. What bonds are polar?
Look for:
O-H
C-O
or N-H…
…bonds in a molecule

47. Attraction between molecules
Polarity provides attraction between molecules
Weak chemical bonds
Hydrogen bonds-- Hydrogen is attracted to the negative portion of polar molecule

48. Hydrogen Bonds
Causes surface tension in water
Figure 2.9

49. Reactants form products
Chemical Reactions
Reactants form products

50. Reactants form products
Chemical Reactions
Reactants form products
A + B  C + D

51. Reactants form products
Chemical Reactions
Reactants form products
A + B  C + D

52. Reactants form products
Chemical Reactions
Reactants form products
A + B  C + D

53. Patterns of Chemical Reactions
Synthesis reaction (A + BAB)
Atoms or molecules combine
Energy is absorbed
Decomposition reaction (ABA + B)
Molecule is broken down
Chemical energy is released

54. Synthesis and Decomposition Reactions
Figure 2.10a

55. Synthesis and Decomposition Reactions
Figure 2.10a

56. Synthesis and Decomposition Reactions
Figure 2.10b

57. Synthesis and Decomposition Reactions
Figure 2.10b

58. Patterns of Chemical Reactions
Exchange reaction (AB + CAC + B)
Involves both synthesis and decomposition reactions
Switch is made between molecule parts and different molecules are made

59. Patterns of Chemical Reactions
Figure 2.10c

60. Patterns of Chemical Reactions
Figure 2.10c