Download 3.3 Energy and the Environment

Chapter 3 – The Physical Science of the Environment
Chapter 3 Outline
• Chemistry
– Atoms and Elements
– Water
– Organic Molecules
• Energy
– Laws of
Thermodynamics
– Forms of Energy
• Earth Science
– Structure of Earth
– Lithosphere
– Atmosphere
• Sun
– Source of Energy
• Weather and
Climate
3.1 Chemistry of the Environment
• Atoms–basic unit of matter
– Made of three particles
• Protons
– In central nucleus, has positive charge
• Neutrons
– In central nucleus, electrically neutral
• Electrons
– Surrounds nucleus, has negative charge
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Overall electric charge neutral
– Positive protons balance negative electrons
• All three particles have mass
– Protons and neutrons have most mass
• 1,000 times more mass than electrons
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Elements are made of one type of atom
• Number of protons determine
Characteristics and name
• 92 naturally occurring elements
• Represented by a symbol
– H, hydrogen
– C, carbon
– O, oxygen
– N, nitrogen
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Isotopes
– Same number of protons, different number of
neutrons
• Carbon has 6 protons, may have 6, 7, or 8
neutrons
• Different weights useful in science
• Radioactive isotopes
• Some unstable, decay at steady rate, emit
radiation
• Half-life: time it takes for half of the atom to decay
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Ions
– Atom gained or lost an electron
– Results in overall charge
• Gained electron = negative charge
• Lost electron = positive charge
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Molecules
– Two or more atoms combined
• Oxygen (O2), nitrogen (N2)
• Compounds
– Molecules made from more than one element
• Carbon dioxide (CO2), water (H2O)
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Chemical bonds hold molecules together
– Covalent bonds
• Atoms share electrons
• Strong bond
• Some molecules share electrons equally
– Molecule nonpolar
• Example: O2
• Others do not share equally
– Molecule polar, resulting in partial charges
• Example: H2O
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Common Molecules
13
3.1 Chemistry of the Environment
• Chemical bonds hold molecules together
– Ionic bond
• Strong bond
• Electron transferred between atoms
• Termed ionic compounds or salts
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Dipole bonds
– Weaker bonds
– Between atoms and molecules
• Result of shifts of charge
– Many biological functions
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Water–important to life
– Polar molecule
• Forms dipole bonds with other water molecules
– Gives water unique properties, stability
• An excellent solvent
– Many biological functions use water as solvent.
© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Water–important to life
– Acids and bases
• Water dissociates into H+ and OH–
• Chemicals (acid/base) may shift amounts
– Shift measured by pH scale
• pH of solution affects biological functions
© 2013 Pearson Education, Inc.
Increasingly basic
(lower H+ concentration)
14 1.0 M NaOH
Increasingly acidic
(greater H+ concentration)
Neutral
[H+] =
[OH–]
13
Ammonia
Household ammonia
12
11
Milk of magnesia
10
Baking soda
9
8 Seawater
Human blood
7 Pure water
Milk
6
5
4
3
2
1
Tomatoes
Wine
Vinegar, colas
Lemon juice
Stomach acid
0 pH scale
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Organic molecules
– Carbon atom covalently bonded to hydrogen
and other atoms
– Primary structural and function component of
life
– Range in size
– Inorganic molecules not made of carbon and
hydrogen
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Organic molecules–types
– Hydrocarbons
• Only made of carbon and hydrogen
– Carbohydrates
• Made of carbon, hydrogen, oxygen
• Sugars, (CH2O)n, with n between 3 and 7
• Glucose (C6H12O6) the basic form of energy for
most organisms
• Sugars known as saccharides
© 2013 Pearson Education, Inc.
Oxygen
Hydrogen
Carbon
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Organic molecules–types
– Lipids
• Long chains of carbon and hydrogen and a shorter
region with one to several oxygen molecules
– Fats and oils
– Nonpolar
– Lipids not water soluble
– Important energy storage
© 2013 Pearson Education, Inc.
Polar region
Phosphorus
Oxygen
Carbon
Hydrogen
Nonpolar
region
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Macromolecules
– Small organic molecule linked together
• Polymers
– Linked together in long chains
• Polysaccharides
– Polymers of simple sugars
• Starch
• Cellulose
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Macromolecules
– Proteins
• Polymers of amino acids
• 20 amino acids–same base structure
– Amino group (–NH2)
– Carboxylic acid group (–COOH)
• Proteins made of chains of 100 to 1,000+ amino
acids
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Macromolecules
– Proteins
– Fold to particular shapes yielding function
– Structural or functional
– May act as catalysts
• Termed enzymes
• Almost all biological reactions use enzymes
© 2013 Pearson Education, Inc.
Typical amino acids
Acid group
Amine group
Alanine
Amino acids are linked to
form a protein chain
Glutamic acid
Protein chains assume a
three-dimensional structure
© 2013 Pearson Education, Inc.
3.2 The Organic Chemistry of Life
• Nucleic acids
– Polymers of nucleotides
• 5-carbon sugar, phosphate group, and nitrogenous
base
– Deoxyribonucleic acid (DNA)
• Hereditary material
• Traits coded in sequence of bases
– adenine (A), thymine (T), cytosine (C), and guanine (G)
© 2013 Pearson Education, Inc.
Complementary
base pairing
Sugar-phosphate
“backbone”
Complementary
base pairs
© 2013 Pearson Education, Inc.
T
A
G
C
C
G
T
A
T
A
C
G
G
C
A
T
T
A
C
G
T
A
G
C
T
A
G
C
T
A
The double helix
T
A
G
C G
A
T
A
T
C
G
G
T
T
C
T
A
C
A
G
A
T
G
A
T
3.2 The Organic Chemistry of Life
• Nucleic acids
– Ribonucleic acid (RNA)
• Structure similar to DNA
• Protein synthesis
– Transcription
• DNA code to RNA
– Translation
• RNA code to protein
• Triplet sequences code for amino acids
© 2013 Pearson Education, Inc.
DNA
Replication
Transcription
RNA
Translation
Protein
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Energy
– Capacity to do work
• Work
– Force applied to an object over a distance
– Potential energy
• Stored energy
– Kinetic energy
• Energy in motion
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Laws of Thermodynamics
– First law
• Energy can be neither created nor destroyed; can
be transformed
– Second law
• Energy transformations increase disorder
– Entropy
– Energy often lost as heat
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Consequences of the Laws of
Thermodynamics
– Total energy contained in the universe
remains the same (energy conservation)
– But, energy transformations result in
increased disorder and useful energy is lost
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Electromagnetic radiation
• Energy moves as photons in waves
• Electromagnetic spectrum–entire range of
wavelengths
– Gamma rays, X-rays, visible light, radiation, infrared,
microwaves, radiowaves
© 2013 Pearson Education, Inc.
Electromagnetic Spectrum
• Intense energy has short wavelengths.
• Lower energy has longer wavelengths.
36
3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Heat
• Kinetic energy of molecules
• Temperature
– Average kinetic energy
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Heat can move in four ways
•
•
•
•
Conduction
Convection
Radiation
Latent heat transfer
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Forms of energy
– Chemical energy
• Potential energy
• Breaking and forming of chemical bonds
– Photosynthesis assembles carbohydrates
– Potential energy in glucose bonds
– When needed, energy released by respiration
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Forms of energy
– Nuclear energy
• Energy in the structure of matter
– Nuclear fission
• Nucleus of atom split, creating two smaller atoms
and releasing vast amounts of kinetic and
electromagnetic energy
– Nuclear fusion
• When atoms collide and fuse
• Process that powers the sun
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Units of energy
– Energy is measured in different units
• Joule (J)–energy to support 1kg mass
• Calorie (cal)–energy to raise 1 g of water 1 ºC
• Watt-hour (Wh)–amount of electricity used for an
hour at 1 joule per hour
© 2013 Pearson Education, Inc.
3.4 The Planet Earth in Context
• Formation of solar system
• Sun began forming 4.6 billion years ago
– The gases and dust not consumed by sun
became planets and other objects
• Planet-like objects
• Asteroids
• Comets
© 2013 Pearson Education, Inc.
Earth is a Layered Sphere
 Its core has an interior
composed of dense, intensely
hot metal that generates a
magnetic field enveloping the
earth.
 Its mantle is a hot, pliable
layer surrounding and less
dense than the core.
 Its crust is a cool,
lightweight, brittle outermost
layer that floats on top of the
mantle.
3.5 Earth's Structure
• Building and moving continents
– Crust is slowly moving
– Tectonic plates
• Pieces of crust that float on mantle
• Contents embedded in plates
© 2013 Pearson Education, Inc.
Tectonic Processes and Shifting Continents
• Upper layer of mantle has convection
currents that break crust into plates
• Slowly slide across earth
– Pull apart
• forms ridges, ocean basins
– Push together
• mountain ranges
– Slide past each other
• earthquakes
• Oceanic plate collides with Continental
– continental rides up over seafloor
– oceanic plate subducts and melts, rise back
as magma
• Subduction zones - deep ocean trenches and
volcanoes
Tectonic Processes
Pangea: The Super-continent
x
Geologists
suggest that
several times in
earth's history
most, or all, of
the continents
gathered to
form a single
super-continent,
Pangea,
surrounded by a
single global
ocean.
© 2013 Pearson Education, Inc.
3.5 Earth's Structure
– Tectonic plates meet at boundaries
• Transform fault boundaries
– Plates slide past
– Sites of earthquakes
– Divergent boundaries
• Plates spread apart
– Convergent boundaries
• Plates come together
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Earth has gravity to hold atmosphere
• Earth's unique atmosphere supports life
– Composition of gases
•
•
•
•
78% nitrogen
21 % oxygen
0.039% carbon dioxide
Water vapor
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Layers of atmosphere
– 480 km deep (300 miles)
– Air at surface compressed by gases above
– Atmospheric pressure
– Pressure decreases as altitude increases
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Layers of atmosphere
– Troposphere
• Lowest layer
• Life located here
• Temperature drops with elevation
– Stratosphere
• 11–48 km
• Temperature increases approaching ozone
• Ozone layer located here
– Protects life from ultraviolet radiation
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Layers of atmosphere
– Mesosphere
• Above stratosphere
• Air temperature drops again (173 ºC) at 90 km
– Thermosphere
•
•
•
•
Extends out to space
Above 150 km gas density so low no friction
International Space Station orbits here
Aurora occurs here
© 2013 Pearson Education, Inc.
Satellites orbit here
Height above sea level
Average temperature
120 km / 75 mi
–60° C / –76° F
110 km / 68 mi
–10° C / –14° F
100 km / 62 mi
–80° C / –112° F
90 km / 56 mi
–90° C / –130° F
80 km / 50 mi
–80° C / –112° F
70 km / 43 mi
–50° C / –58° F
Thermosphere
Mesophere
–30° C / –22° F
60 km / 37 mi
50 km / 31 mi
–10° C / –14° F
Negligible pressure
40 km / 25 mi
–20° C / –4° F
Stratopause
5 mb
30 km / 19 mi
–40° C / –40° F
3 mb
–60° C / –76° F
Tropopause
20 km / 12 mi
10 mb
10 km / 6 mi
60° C / 76° F
50 mb
Sea level
B
200 mb
A
1000 mb
© 2013 Pearson Education, Inc.
15° C / 59° F
The atmosphere
has four distinct
zones of
contrasting
temperature.
3.6 Earth's Atmosphere
• Water in the atmosphere
– Water vapor (H2O) ~ 1% of molecules
– Varies predictably
• Vapor pressure
– About 10 mb at sea level
– Ranges 0.01 mb–40+ mb
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Saturation vapor pressure
– Temperature dependent
• Amount of water air can hold raises with
temperature
– Above saturation vapor pressure
– Water condenses
• Rain, fog
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Relative humidity
– Extent air is saturated with water
– Expressed as percentage
• Dew point
– Temperature where humidity is 100%
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
3.7 Earth's Energy Budget, Weather, and
Climate
• Energy budget
– Measures all energy entering and leaving
Earth
– Balances over time
• Solar radiation
– 30% reflected to space
– 70% absorbed by land, sea, and air
• Absorbed heat eventually radiated back to space
as infrared radiation
© 2013 Pearson Education, Inc.
Energy and the "Greenhouse Effect"
Reflected by
atmosphere 6%
Reflected by
clouds 20%
Reflected from
Earth’s surface 4%
Absorbed by
clouds 3%
Conduction and
rising air 7%
Radiated to space from clouds
and atmosphere 64%
Radiated
Carried to clouds
to space from
and atmosphere
Earth
Incoming
solar energy
100%
Absorbed by atmosphere 16%
Radiation absorbed
by atmosphere 15%
Absorbed by land and oceans 51%
© 2013 Pearson Education, Inc.
3.7 Earth's Energy Budget, Weather, and
Climate
• Weather and climate
– Climate
• Long-term atmospheric conditions
– Temperature, humidity, average rainfall
– Weather
• Short-term variations local atmospheric conditions
– Thunderstorms
© 2013 Pearson Education, Inc.
3.7 Earth's Energy Budget, Weather, and
Climate
• Wind cells
– Sunlight unequally heats Earth
– Difference causes differing temperature and
pressure
• Air circulates in large convection currents
– Climate influenced
© 2013 Pearson Education, Inc.
3.7 Earth's Energy Budget, Weather, and
Climate
• Wind cells
– Intertropical convergence zone
• Warm, humid air rises, then cools
• Causes large amounts of rain
– Air then moves toward poles
– Forms convection cells flanking equator
• Hadley cells
© 2013 Pearson Education, Inc.
3.7 Earth's Energy Budget, Weather, and
Climate
• Wind cells
– At 30–35o latitude, cool air descends
• Air is dry
• Forms many deserts
– Ferrel cells
• Between 30 and 60o latitude
– Polar cells
• Between 60 and 90o latitude
– Change in wind direction, Earth's rotation
• Coriolis effect
© 2013 Pearson Education, Inc.
Convection and Atmospheric Pressure
•
•
•
•
Evaporation
Latent heat
Condensation
Convection
currents
• Air pressure
differences
• Coriolis effect
Tornadoes
are local
cyclonic
storms
caused by
rapid
mixing of
cold, dry air
and warm,
wet air.
3.7 Earth's Energy Budget, Weather, and
Climate
• Earth tilted on axis 23.5 degrees
– Causes differential heating throughout the
year
– Causes wind cells to shift north or south
• Differences in rainfall and temperature
• Temperature difference more extreme at center of
continents and higher at latitudes
© 2013 Pearson Education, Inc.
March
March equinox: neither
pole tilts toward the sun
December
June
September
Summer solstice:
Northern
hemisphere tilts
toward the sun September
equinox: neither
pole tilts toward
the sun
© 2013 Pearson Education, Inc.
Winter solstice:
Northern
hemisphere tilts
away from the
sun
23.5°