1. Chapter 2

3. Remember…..
Organism
organ system
Organs
Tissues
Cells
Molecules
atoms

4. Matter = anything that
1. has mass
2. takes up space

5. 3 Forms of Matter
Holds Shape
Fixed volume
Container shape
Free Surface
Fixed Volume
Container Shape
Volume of Container

6. Matter composed of basic substances
Elements
1. Specific chemical & physical characteristics
2. Fundamental substances
3. 1 type of atom

7. 92 naturally occurring
elements
11+ Synthetic
elements

8. Primary Elements of Living Things
1. Carbon
2. Hydrogen
3. Nitrogen
4. Oxygen
5. Phosphorus
6. Sulfur
98% 95%

9. Naming of Elements
1. Latin or English
2. Atomic Symbol =
1 or 2 letter abbreviation
Carbon = C
Hydrogen = H
Oxygen = O
Sodium = Na
Iron = Fe
Potassium = K
Nitrogen = N

11. Atom =
smallest particle of an element
that displays properties of that element

12. John Dalton: Atomic Theory
Early 1800’s
“All Matter is
composed of
atoms”

13. Structure of an Atom:
(Sub-atomical Particles)
Protons
Neutrons
Electrons

14. Sub-atomic Particles: Charges
Protons = Positive Charges
Neutrons - Neutral Charges
Nucleus
Electrons – Negative Charges

15. Atomic Number & Weight
Atomic number = number of protons
(# protons = # electrons)
Atomic weight (mass) = protons + neutrons in an atom.

16. Therefore, if…..
Atomic number = number of protons
Atomic weight = protons + neutrons
Then………
atomic weight - atomic number = # of neutrons
(P + N) (# of P) (# of N)

17. Isotopes
Isotopes = atoms of same element with:
same atomic number (# protons),
different atomic weight (# protons & neutrons)
What is different?

18. Isotopes
1. Unstable…..
• break down
2. Give off radiation
3. Used in medicine
& dating fossils

19. Electron Configuration
determines properties of an atom
• # of electrons = # of protons.
• Electron = energy in an atom
• Electrons have same weight & charge,
vary in energy content
• Farthest from nucleus =
greatest “potential energy”

20. Atomic Energy Levels
Orbital: where electrons found.
Shells: in orbitals, found in shells

21. Octet Rule
The first shell: full = 2 electrons.
Beyond first shell: full = 8 (or multiples) electrons

22. Molecule – smallest part of element or
compound that has properties of that
element or compound.
Compound - Two or more different
types of atoms that react or bond
together.

23. Chemical Formulas
1 Symbols for composition of substance.
ex: Hydrogen Cloride = HCl
2 More than 1 atom of same kind = subscript
ex: Water or H2O

24. Determining Reactivity
outer (valence) shell not full = reactive
outer (valence) shell full = not reactive
(inert)

25. outer shell = valence shell
Atoms want a full outer shell.
To complete outer shell, an atom may:
1. Give up an electron
2. Accept an electron
3. Share an electron

26. chemical bond =
transfer or sharing
electrons with another
atom

27. Electrons possess
energy
chemical bond = energy relationship

28. **Energy Relationship **
1. Energy required to form bond
2. Energy stored in chemical bonds.
3. Energy released when bond is
broken.
This concept is a top priority for living
organisms.

29. Types of Reactions
Endergonic reactions – small
molecules bonded to form large
molecules.
Energy is required.
Exergonic reactions – large molecules
broken down into small molecules.
Energy is released.

30. Chemical reactions indicated by
chemical equations
2H2 + O2  2H2O
reactants products
Equal # of atoms exist on both sides

31. Types of Reactions
• Synthesis A + B  C
• Decomposition AB  A + B
• Exchange AB + CD  AD + CB
• Reversible A + B  AB
• Oxidation loss of electron (break down)
• Reduction gain of electron (synthesis)

32. Chemical Bonds
•Ionic
•Covalent
•Polar Covalent
•Hydrogen

33. Ionic Bonding
=
transfer of electrons

34. Remember…
Atoms are electrically balanced
Electron transfer  charge imbalance
creates ions (charged atom)
ionic bond = attraction of - & +

35. 3 P +
7 P +
9 P +3 P + e-
e-e-
e- e-
e-
e-
e-
e-
e-
e-
e-

36. 3 P +
7 P +
9 P +3 P + e-
e-e-
e- e-
e-
e-
e-
e-
e-
e-
e-e-e-
3 P +
3 + and 2 –
NET = 1+
10 - and 9+
NET = 1-

37. Covalent Bonding =
sharing of electrons

38. 1. Atoms linked like a chain.
2. Very strong bonds
(single, double, etc)
3. Found in organic molecules.
(Hydrogen, Oxygen & Carbon)

39. e-
e-

40. e-
e-

41. e-
e-
e-e-
e-
e-e-
e-
e-
e-

42. e-
e-
e-
e-
e-
e-
e-
e-
e- e-

43. Polar Covalent Bonds
=
Unequal sharing
of electrons

44. • Molecule formed has both:
positive end
negative end
• “polar” molecule
• Water

48. hydrogen bond =
a slightly “+” hydrogen atom
attracted to
slightly “-”atom in other molecule

49. • Weak and easily broken
• Many together can be quite strong
• Usually the bond is with O or N
• NOT electron sharing or donating…. It is
an ATTRACTION to neighboring molecule
• Illustrated by a broken dotted line.

51. • http://programs.northlandcollege.edu/biolo
gy/Biology1111/animations/hydrogenbond
s.html

52. Chemical properties
of water
are essential to life
Living things 70–90%
water

53. Properties of Water
• Resists changes in temperature
gains and loses heat slowly
Ocean circulation = Europe’s mild winters even though it is further north than Canada.

54. Properties of Water
• Resists change in state
tends to remain liquid
high freezing point & high boiling point

55. Properties of Water
Universal Solvent
Most substances associate with water.
Facilitates chemical reactions.
solute + solvent = solution

56. Hydrophilic = “water” “loving”
(attracted to water molecules)
Hydrophobic = “water”
“fearing”
(repelled by water molecules)

57. Properties of Water
• Cohesive and Adhesive
molecules stick together & to other molecules
(effective as a transport medium)

58. Properties of Water
• High Surface Tension
Surface of water hard to break.
Basilisk Lizard

59. http://www.youtube.com/watch?v=KSLUwmJOo_M

60. Properties of Water
• Frozen water
less dense than
liquid water.
Ice (solid water)
floats on liquid
water.

61. Water has a slight tendency
to
“fall apart”
or
DISSOCIATE

62. OH- called hydroxide ion
H+ called hydrogen ion
(actually H30+)
Water dissociates into equal
numbers of:

65. Others dissociate in water
may release
unequal
amounts of “+” or “-” ions

66. Acids = produces H+ ions
taste sour
can be corrosive
Bases = can accept H+ ions
taste bitter
feel slippery

67. Acidity or Alkalinity
=
measure of relative amount of
H+ and OH- ions
dissolved in a solution

68. pH scale = indicate acidity
and basicity of a solution
Scale ranges from 0 to 14
0-3 is very acidic
7 is neutral
11-14 is very basic or alkaline

70. Control of pH
is important to organisms!!
• Enzymes function only within a narrow pH
range; usually neutral
• Buffers neutralize acids or bases in organisms
to help control pH
(by taking up or releasing H+ ions)