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Worldview: what the world means to me (and my kind)

•  Religion •  Resource abundance •  Standard of living •  Interaction with ‘outgroups’ •  Government •  Education •  Personal background And….?

Religion (2000)

•  84% of the world is religious (5 billion people). 2/3 belong to the ‘big three’

• Christian: 33%, (2 billion) •  Islam: 20%, 1.2 billion • Hindu: 14 %, 800 million

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Quality of life indicators

GDP (Gross Domestic Product) Life expectancy Infant mortality Drinking water Female Literacy Birthrate (fertility rates)

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Haiti and Costa Rica: a case study

•  History •  Religion •  Occupation •  Government •  Status today

How we think, what we believe, how we are governed, all influence how we behave,

including our behavior towards our environment

What’s a ‘system’ •  Network of interdependent components and

processes with materials and energy flowing from one component to another.

•  These processes are biological, physical and chemical.

•  Ultimately, the amount of energy and matter in vrs. what goes out, affects what can be supported in a system: open vrs. closed systems

•  Let’s take a look at these components

Systems cont.

•  Open systems – most are to some degree. Some inputs are also ‘output’

•  Closed systems – exchange no matter or energy with surroundings (rare)

•  Some systems (eg. Large ones) can absorb large inputs without altering much.

•  But most have a threshold that can be difficult to measure/predict

Feedback loops: ecological, physiological…

•  Positive feedback: positive change in a state variable (eg. Nutrient input) leads to a positive response (higher growth etc.). These can ‘run away’ if not controlled. Eutrophication.

•  Negative feedback: Increase leads to decrease – too many predators=few prey=lower population of predators. These can lead to stability (homeostasis)

What is an ecosystem in balance?

Stability?

•  Resilience •  Phase (state) shifts

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What does this have to do with chemistry: matter and energy?

•  Chemistry is ‘how the world works’, part I •  It occurs at a level we can’t really see, but its

effects can be very tangible •  The behavior of matter and energy is NOT

dependent on worldview •  How you interpret this behavior IS •  How you act IS

•  Let’s try and understand the basics…

What is Energy then?

•  The ability to do work, or cause a temperature change (heat transfer)

•  Kinetic energy: energy of mass and motion. Temperature is a measure of KE of a molecule

•  Potential energy: stored energy. Energy in chemical bonds for example

Thermodynamics

•  First Law: –  Energy in = Energy out –  Energy cannot be created or destroyed–it just changes

form •  Second Law:

–  As energy changes form, some of it degrades –  Higher energy form to a lower one

•  Law of conservation of matter: –  Matter is not created or destroyed, it just changes

physically or chemically

Trophic levels–energy flow through ecosystems

•  Autotrophs: primary producers •  Heterotrophs: consumers

– Primary, secondary, tertiary •  Decomposers •  Food webs depict complex relationships:

omnivores? Many cross trophic levels

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Energy exchange in ecosystem Figure 2.11

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Trophic levels Figure 2.14

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Figure 54.5 An idealized pyramid of net productivity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Trophic pyramid Figure 2.17

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Energy pyramid/biomass period Figure 2.16

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Matter quality (as a resource)

• What is matter? • Atoms, molecules and compounds •  ‘High quality’ matter is organized,

concentrated and easy to access •  ‘Low quality’ is dilute and

disorganized

‘Law’ of conservation of matter

•  Matter is recycled •  Matter is not created or destroyed, just

changes form •  Sometimes the ‘forms’ can change to be

more or less toxic •  Some ‘forms’ change more quickly due to

chemical reactions

Phases of matter: heat and pressure change states

•  Solid: dense and ‘organized’. Gold ore vrs. ‘Panning’ in a river

•  Liquid: Atoms hit each other often, but less dense

•  Gas: Atoms vibrate in their own space: even less dense

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But water is different… •  Solid: less dense! It

floats •  Liquid: •  Gas: least dense

•  Water doesn’t behave like most substances…

•  Movement of atoms/molecules

Biological Chemistry

•  Inorganic Molecules •  Organic Molecules: carbon - creating large,

complex, diverse molecules –  Carbohydrates –  Lipids –  Proteins –  Nucleic Acids

•  Sodium Chloride •  Water •  Nitrous oxide •  Ammonia •  Hydrogen sulfide

•  No carbon

Inorganic molecules

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Organic compounds

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Organic molecules Figure 2.6

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Chemical forms of matter

•  Elements: building blocks • Atoms: The smallest units • Molecules: atoms as a single unit • Compounds: • Mixtures: compounds and

elements: air

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Molecules and compounds Figure 2.4

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Elements and compounds

Matter: Elements and Atoms

•  Matter is made of Elements •  An element is a substance that cannot be

broken down. •  Elements are made up of atoms

– Protons (+) – Neutrons (----) – Electrons (-) smallest

•  The nature of the atom determines its reactivity….

Mercury (Hg) is an element

•  It can combine with organic or inorganic molecules too

•  Bacteria and chemical reactions can change mercury into methylmercury (toxic) [CH3Hg]+

•  Fish can become toxic by eating smaller organisms that have absorbed it: biomagnification

•  Law of conservation of matter and systems

Elemental mercury (Hg) and [CH3Hg]+ methylmercury

Salt HgCl2

Mercury in tons (1998) EPA (total 81 tons in 2002) e

Biomagnification

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Electrons occupy ‘shells’ •  8 in the outermost shell is ideal! •  How do they get there? Share….

Matter: Atoms

•  Protons and neutrons are in the center of an atom = nucleus

•  Electrons move around the nucleus in orbitals (2 per)

•  Orbitals are grouped in shells •  Movement of electrons between shells

either requires or releases energy

Atomic Structure •  Elements combine to form Compounds

-Compound = NaCl Elements = Na and Cl •  Each element is made of one kind of atom

which is different from every other •  Atoms are made of protons, electrons and

neutrons •  Atomic numbers •  Orbitals and electron shells

Atoms of the four elements �most common in life

Bonds and reactivity

Bonds can form spontaneously to create stability in atoms

Bonds can also form when molecules are dissociated, such as in water, or by some other chemical process, and the atoms come into contact with other atoms to which they bond. Some persistent environmental chemicals do this

Or, bonds can be ‘made’ by using an energy source (eg. Photosynthesis, and the synthesis of sugar

Some molecules and compounds persist, and behave based on solubility and hydrophobic or hydrophilic tendencies

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Energy exists in chemical bonds

• Energy can be harvested from chemical bonds (ATP)

• Energy rich molecules can be made using energy (photosynthesis and respiration)

Molecules and Bonding

•  Why do atoms bond together to form molecules? •  Ionic Bonding

–  Ions donating electrons •  Covalent Bonds

– Sharing electrons – Complex Molecules – Polar and Non-polar Covalent Bonds

• Electronegativity •  Hydrogen bonds

Molecules and Bonding •  Reactive elements can

join together •  Ionic Bonds

–  Ions donating electrons – One becomes + One becomes –

– These now attract each other and bond

Molecules and Bonding •  Reactive elements can

join together •  Ionic Bonds

– Donating electrons •  Covalent Bonds

– Sharing electrons – Polar/non-polar

•  Hydrogen bonds – Polar bonds

Polar and Non-polar bonds

•  Polar and Non-polar Covalent Bonds – Electronegativity

Hydrogen Bonds

•  Polar molecules can be weakly attracted to each other and form Hydrogen Bonds

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Biological Significance of H-bonds:

•  An environment for the chemistry of life. •  Solubility - polar molecules can dissolve

into solution because of H-bond formation whereas non-polar molecules cannot

•  Stability - Some polar molecules form H-bonds internally. These attractive forces serve to strengthen their internal structure.

Water is special……

The Magic of Water 1. Cohesion and Adhesion

Water is attracted to other water and to other polar substances by the charges in the structure. “Hydrophilic” = water loving.

2. Excellent biological solvent

3. High heat capacity 4. High thermal conductivity 5. Less dense when frozen

The Magic of Water

The water molecule is polar Some molecules and compounds persist, and behave based on solubility and hydrophobic or hydrophilic tendencies

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Plastics

PCBs

PCBs and DDT are hydrophobic They do not dissolve in water

Hydrophobic molecules tend to ‘stick together’

•  The making and breaking of chemical bonds - changing the composition of matter

•  Some reactions progress to completion, but MOST are reversible

•  Concentration of reactants can affect the rate of the reaction

•  Chemical equilibrium •  Activation energy - some need it •  Catalysts - enhance or speed up the reaction

Chemical reactions

Chemical Reactions

2H2 + O2 = 2H20

Photosynthesis/Respiration

Photosynthesis: •  Plants use carbon

dioxide and produce starch and oxygen

H2O + CO2 = Starch/sugar + O2

Respiration •  Animals use starch/

sugar and oxygen, and produce carbon dioxide

Starch/sugar + O2 = H2O + CO2

6CO2 + 6H2O + = C6H12O6 + 6O2

How do we get to this energy?

•  Cellular Respiration – Aerobic (w/ oxygen) need for efficient transfer

6CO2 + 6H2O + = C6H12O6 + 6O2

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What you have learned so far…

Matter has mass, and is conserved, though can change It is comprised of atoms and molecules

Energy can do work, and is also conserved, though can change state

Energy is stored in chemical bonds

Atoms have protons, neutrons and electrons. Electron arrangements are particularly important in determining reactivity. Ions (+ and -) are very reactive

Bonding of atoms to others helps stabilize the atoms, and fill their electron shells – this makes molecules

What you have learned so far… Some molecules are persistent in the environment, and can cause health concerns. They can also biomagnify. PCBs are an example.

Some molecules are hydrophobic (water hating), some are hydrophilic (water loving). These characteristics can be very important .

Chemical reactions move forward in a variety of ways: concentrations, activation energy, catalysts

Water is a universal solvent and an excellent medium for chemical reactions, and has a high heat capacity. The water molecule is polar.

Acids and bases

•  Acids give up hydrogen ions (H+) •  Bases readily bond with these H+.

Remember ionic bonds… •  Acids and bases are highly reactive •  For example H+ breaks down CaCO3

(calcium carbonate).

Chemical Dissociation

•  Salts, Acids, and Bases

•  pH

•  Buffers

The physics and chemistry of adding acid to the ocean are well known. “Gigatons of acid are lowering the pH of the worlds oceans, humans are totally responsible, and the more carbon dioxide we emit, the worse it’s going to get”

Science, June 2010

Unprecedented in Earth’s history

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.1 Ph unit decline in acidity since industrialization (to the current 8.1). This represents a 30% increase in surface ocean acidity.

It is lower now than in the past 20 million years, and its falling fast.

Predicted to fall to 7.8 by the end of the century, an increase of 150%.

What moves chemical reactions forward?

•  High concentrations can drive chemical reactions, such as with acidification. Other things like heat energy, physical force etc. can also drive chemical reactions.

•  # of molecules in a specific volume •  Diffusion and Osmosis:

– Diffusion is the net movement of molecules from areas of high to low concentration

– Passive - requires no energy input – Osmosis is the movement of water through a

membrane that prevents solutes (large molecules) from passing. Net movement is from high to low concentrations

Concentrations of solutions Diffusion

Hypertonic Hypotonic Isotonic

Diffusion goes in all directions Osmosis- passive transport of

water across a membrane

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Knowledge (scientific) provides us with a basis from which to make decisions and take action. At what point do we have enough knowledge to make those decisions and take that action?

Scientific process can move us forward but also be an excuse for inaction

Know where your knowledge comes from…