Chapter 2
Remember…..
Organism
organ system
Organs
Tissues
Cells
Molecules
atoms
Matter = anything that
1. has mass
2. takes up space
3 Forms of Matter
Holds Shape
Fixed volume
Container shape
Free Surface
Fixed Volume
Container Shape
Volume of Container
Matter composed of basic substances
Elements
1. Specific chemical & physical characteristics
2. Fundamental substances
3. ...
92 naturally occurring
elements
11+ Synthetic
elements
Primary Elements of Living Things
1. Carbon
2. Hydrogen
3. Nitrogen
4. Oxygen
5. Phosphorus
6. Sulfur
98% 95%
Naming of Elements
1. Latin or English
2. Atomic Symbol =
1 or 2 letter abbreviation
Carbon = C
Hydrogen = H
Oxygen = O
So...
Atom =
smallest particle of an element
that displays properties of that element
John Dalton: Atomic Theory
Early 1800’s
“All Matter is
composed of
atoms”
Structure of an Atom:
(Sub-atomical Particles)
Protons
Neutrons
Electrons
Sub-atomic Particles: Charges
Protons = Positive Charges
Neutrons - Neutral Charges
Nucleus
Electrons – Negative Charges
Atomic Number & Weight
Atomic number = number of protons
(# protons = # electrons)
Atomic weight (mass) = protons + neutro...
Therefore, if…..
Atomic number = number of protons
Atomic weight = protons + neutrons
Then………
atomic weight - atomic numbe...
Isotopes
Isotopes = atoms of same element with:
same atomic number (# protons),
different atomic weight (# protons & neutr...
Isotopes
1. Unstable…..
• break down
2. Give off radiation
3. Used in medicine
& dating fossils
Electron Configuration
determines properties of an atom
• # of electrons = # of protons.
• Electron = energy in an atom
• ...
Atomic Energy Levels
Orbital: where electrons found.
Shells: in orbitals, found in shells
Octet Rule
The first shell: full = 2 electrons.
Beyond first shell: full = 8 (or multiples) electrons
Molecule – smallest part of element or
compound that has properties of that
element or compound.
Compound - Two or more di...
Chemical Formulas
1 Symbols for composition of substance.
ex: Hydrogen Cloride = HCl
2 More than 1 atom of same kind = sub...
Determining Reactivity
outer (valence) shell not full = reactive
outer (valence) shell full = not reactive
(inert)
outer shell = valence shell
Atoms want a full outer shell.
To complete outer shell, an atom may:
1. Give up an electron
2....
chemical bond =
transfer or sharing
electrons with another
atom
Electrons possess
energy
chemical bond = energy relationship
**Energy Relationship **
1. Energy required to form bond
2. Energy stored in chemical bonds.
3. Energy released when bond ...
Types of Reactions
Endergonic reactions – small
molecules bonded to form large
molecules.
Energy is required.
Exergonic re...
Chemical reactions indicated by
chemical equations
2H2 + O2  2H2O
reactants products
Equal # of atoms exist on both sides
Types of Reactions
• Synthesis A + B  C
• Decomposition AB  A + B
• Exchange AB + CD  AD + CB
• Reversible A + B  AB
...
Chemical Bonds
•Ionic
•Covalent
•Polar Covalent
•Hydrogen
Ionic Bonding
=
transfer of electrons
Remember…
Atoms are electrically balanced
Electron transfer  charge imbalance
creates ions (charged atom)
ionic bond = at...
3 P +
7 P +
9 P +3 P + e-
e-e-
e- e-
e-
e-
e-
e-
e-
e-
e-
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-
Covalent Bonding =
sharing of electrons
1. Atoms linked like a chain.
2. Very strong bonds
(single, double, etc)
3. Found in organic molecules.
(Hydrogen, Oxygen ...
e-
e-
e-
e-
e-
e-
e-e-
e-
e-e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
e- e-
Polar Covalent Bonds
=
Unequal sharing
of electrons
• Molecule formed has both:
positive end
negative end
• “polar” molecule
• Water
hydrogen bond =
a slightly “+” hydrogen atom
attracted to
slightly “-”atom in other molecule
• Weak and easily broken
• Many together can be quite strong
• Usually the bond is with O or N
• NOT electron sharing or d...
• http://programs.northlandcollege.edu/biolo
gy/Biology1111/animations/hydrogenbond
s.html
Chemical properties
of water
are essential to life
Living things 70–90%
water
Properties of Water
• Resists changes in temperature
gains and loses heat slowly
Ocean circulation = Europe’s mild winters...
Properties of Water
• Resists change in state
tends to remain liquid
high freezing point & high boiling point
Properties of Water
Universal Solvent
Most substances associate with water.
Facilitates chemical reactions.
solute + solve...
Hydrophilic = “water” “loving”
(attracted to water molecules)
Hydrophobic = “water”
“fearing”
(repelled by water molecules)
Properties of Water
• Cohesive and Adhesive
molecules stick together & to other molecules
(effective as a transport medium)
Properties of Water
• High Surface Tension
Surface of water hard to break.
Basilisk Lizard
http://www.youtube.com/watch?v=KSLUwmJOo_M
Properties of Water
• Frozen water
less dense than
liquid water.
Ice (solid water)
floats on liquid
water.
Water has a slight tendency
to
“fall apart”
or
DISSOCIATE
OH- called hydroxide ion
H+ called hydrogen ion
(actually H30+)
Water dissociates into equal
numbers of:
Others dissociate in water
may release
unequal
amounts of “+” or “-” ions
Acids = produces H+ ions
taste sour
can be corrosive
Bases = can accept H+ ions
taste bitter
feel slippery
Acidity or Alkalinity
=
measure of relative amount of
H+ and OH- ions
dissolved in a solution
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 ...
Control of pH
is important to organisms!!
• Enzymes function only within a narrow pH
range; usually neutral
• Buffers neut...
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
103 ch 2 briehn rev sp 12
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103 ch 2 briehn rev sp 12

  1. 1. Chapter 2
  2. 2. Remember….. Organism organ system Organs Tissues Cells Molecules atoms
  3. 3. Matter = anything that 1. has mass 2. takes up space
  4. 4. 3 Forms of Matter Holds Shape Fixed volume Container shape Free Surface Fixed Volume Container Shape Volume of Container
  5. 5. Matter composed of basic substances Elements 1. Specific chemical & physical characteristics 2. Fundamental substances 3. 1 type of atom
  6. 6. 92 naturally occurring elements 11+ Synthetic elements
  7. 7. Primary Elements of Living Things 1. Carbon 2. Hydrogen 3. Nitrogen 4. Oxygen 5. Phosphorus 6. Sulfur 98% 95%
  8. 8. 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
  9. 9. Atom = smallest particle of an element that displays properties of that element
  10. 10. John Dalton: Atomic Theory Early 1800’s “All Matter is composed of atoms”
  11. 11. Structure of an Atom: (Sub-atomical Particles) Protons Neutrons Electrons
  12. 12. Sub-atomic Particles: Charges Protons = Positive Charges Neutrons - Neutral Charges Nucleus Electrons – Negative Charges
  13. 13. Atomic Number & Weight Atomic number = number of protons (# protons = # electrons) Atomic weight (mass) = protons + neutrons in an atom.
  14. 14. Therefore, if….. Atomic number = number of protons Atomic weight = protons + neutrons Then……… atomic weight - atomic number = # of neutrons (P + N) (# of P) (# of N)
  15. 15. Isotopes Isotopes = atoms of same element with: same atomic number (# protons), different atomic weight (# protons & neutrons) What is different?
  16. 16. Isotopes 1. Unstable….. • break down 2. Give off radiation 3. Used in medicine & dating fossils
  17. 17. 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”
  18. 18. Atomic Energy Levels Orbital: where electrons found. Shells: in orbitals, found in shells
  19. 19. Octet Rule The first shell: full = 2 electrons. Beyond first shell: full = 8 (or multiples) electrons
  20. 20. 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.
  21. 21. 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
  22. 22. Determining Reactivity outer (valence) shell not full = reactive outer (valence) shell full = not reactive (inert)
  23. 23. 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
  24. 24. chemical bond = transfer or sharing electrons with another atom
  25. 25. Electrons possess energy chemical bond = energy relationship
  26. 26. **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.
  27. 27. 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.
  28. 28. Chemical reactions indicated by chemical equations 2H2 + O2  2H2O reactants products Equal # of atoms exist on both sides
  29. 29. 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)
  30. 30. Chemical Bonds •Ionic •Covalent •Polar Covalent •Hydrogen
  31. 31. Ionic Bonding = transfer of electrons
  32. 32. Remember… Atoms are electrically balanced Electron transfer  charge imbalance creates ions (charged atom) ionic bond = attraction of - & +
  33. 33. 3 P + 7 P + 9 P +3 P + e- e-e- e- e- e- e- e- e- e- e- e-
  34. 34. 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-
  35. 35. Covalent Bonding = sharing of electrons
  36. 36. 1. Atoms linked like a chain. 2. Very strong bonds (single, double, etc) 3. Found in organic molecules. (Hydrogen, Oxygen & Carbon)
  37. 37. e- e-
  38. 38. e- e-
  39. 39. e- e- e-e- e- e-e- e- e- e-
  40. 40. e- e- e- e- e- e- e- e- e- e-
  41. 41. Polar Covalent Bonds = Unequal sharing of electrons
  42. 42. • Molecule formed has both: positive end negative end • “polar” molecule • Water
  43. 43. hydrogen bond = a slightly “+” hydrogen atom attracted to slightly “-”atom in other molecule
  44. 44. • 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.
  45. 45. • http://programs.northlandcollege.edu/biolo gy/Biology1111/animations/hydrogenbond s.html
  46. 46. Chemical properties of water are essential to life Living things 70–90% water
  47. 47. 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.
  48. 48. Properties of Water • Resists change in state tends to remain liquid high freezing point & high boiling point
  49. 49. Properties of Water Universal Solvent Most substances associate with water. Facilitates chemical reactions. solute + solvent = solution
  50. 50. Hydrophilic = “water” “loving” (attracted to water molecules) Hydrophobic = “water” “fearing” (repelled by water molecules)
  51. 51. Properties of Water • Cohesive and Adhesive molecules stick together & to other molecules (effective as a transport medium)
  52. 52. Properties of Water • High Surface Tension Surface of water hard to break. Basilisk Lizard
  53. 53. http://www.youtube.com/watch?v=KSLUwmJOo_M
  54. 54. Properties of Water • Frozen water less dense than liquid water. Ice (solid water) floats on liquid water.
  55. 55. Water has a slight tendency to “fall apart” or DISSOCIATE
  56. 56. OH- called hydroxide ion H+ called hydrogen ion (actually H30+) Water dissociates into equal numbers of:
  57. 57. Others dissociate in water may release unequal amounts of “+” or “-” ions
  58. 58. Acids = produces H+ ions taste sour can be corrosive Bases = can accept H+ ions taste bitter feel slippery
  59. 59. Acidity or Alkalinity = measure of relative amount of H+ and OH- ions dissolved in a solution
  60. 60. 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
  61. 61. 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)
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