Environmental Systems Chapter 2

Earth is a single interconnected system.

TYPES AND STRUCTURE OF MATTER Elements and Compounds Matter is anything that takes up space and has mass and exists in chemical forms as elements and compounds. An atom is the smallest particle that can contain the chemical properties of an element and elements (represented on the periodic table) are the distinctive building blocks of matter. Compounds: two or more elements held together in fixed proportions by chemical bonds.

Atoms Figure 2-4

Atoms The number of protons is called the atomic number. The mass number is the number of protons and neutrons in an atom. Isotopes are when an element has a different mass number (different number of neutrons).

Ions An ion is an atom or group of atoms with one or more net positive or negative electrical charges. The number of positive or negative charges on an ion is shown as a superscript after the symbol for an atom or group of atoms Hydrogen ions (H+), Hydroxide ions (OH-) Sodium ions (Na+), Chloride ions (Cl-)

Compounds and Chemical Formulas Chemical formulas are shorthand ways to show the atoms and ions in a chemical compound. Combining Hydrogen ions (H+) and Hydroxide ions (OH-) makes the compound H2O (dihydrogen oxide, a.k.a. water). Combining Sodium ions (Na+) and Chloride ions (Cl-) makes the compound NaCl (sodium chloride a.k.a. salt).

Nuclear Energy: Radioactivity The nuclei of isotopes can be stable or unstable depending on the mass number of the isotope and the number of neutrons it contains. Unstable isotopes are radioactive. Radioactive isotopes undergo radioactive decay, which is the spontaneous release of material from the nucleus. Radioactive decay changes the element (parent) into another element (daughter). The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope).

Nuclear Changes: Fission Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons. Figure 2-9

Nuclear Changes: Fusion Nuclear fusion: two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus. Figure 2-10

Chemical Bonds There are three types of chemical bonds: covalent, ionic, and hydrogen. Covalent=elements that do not readily gain or or lose electrons form compounds by sharing electrons. Ionic=this involves the transfer of electrons and creates ions where one element become positively charges and another negatively charged. Hydrogen bond= is a weak chemical bond that forms when hydrogen atoms that are covalently bonded to one atom are attracted to another atom on another molecule, there electrons may be shared unequally like water this can create a Polar molecule= on side is more positive and the other side is more negative

Properties of Water Water is amazing and makes up much of the Earth. Its unique molecular structure give it properties that support life. Surface Tension Capillary action Boiling and freezing Ability to dissolve substances

Acids, Bases and ph Acids=contribute hydrogen ions to a solution Base=contributes hydroxide ions to a solution ph scale= is a way to indicate the strength of acids and bases

The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution. Figure 2-5

Conservation of Matter Matter can change from one physical form to another or change its chemical composition. When a physical or chemical change occurs, no atoms are created or destroyed. Law of conservation of matter. Physical change maintains original chemical composition. Chemical change involves a chemical reaction which changes the arrangement of the elements or compounds involved. Chemical equations are used to represent the reaction.

States of Matter The atoms, ions, and molecules that make up matter are found in three physical states: solid, liquid, gaseous. A fourth state, plasma, is a high energy mixture of positively charged ions and negatively charged electrons. The sun and stars consist mostly of plasma. Scientists have made artificial plasma (used in TV screens, gas discharge lasers, florescent light).

Matter Quality Matter can be classified as having high or low quality depending on how useful it is to us as a resource. High quality matter is concentrated and easily extracted. low quality matter is more widely dispersed and more difficult to extract. Figure 2-8

Coal-fired power plant emissions High Quality Low Quality Solid Gas Salt Solution of salt in water Coal Coal-fired power plant emissions Figure 2.8 Examples of differences in matter quality. High-quality matter (left column) is fairly easy to extract and is concentrated; low-quality matter (right column) is more difficult to extract and is more widely dispersed than high-quality matter. Gasoline Automobile emissions Aluminum can Aluminum ore Fig. 2-8, p. 39

Organic Compounds: Carbon Rules Organic compounds contain carbon atoms combined with one another and with various other atoms such as H+, N+, or Cl-. Contain at least two carbon atoms combined with each other and with atoms. Methane (CH4) is the only exception. All other compounds are inorganic.

Organic Compounds: Carbon Rules Hydrocarbons: compounds of carbon and hydrogen atoms (e.g. methane (CH4)). Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms (e.g. DDT (C14H9Cl5)). Simple carbohydrates: certain types of compounds of carbon, hydrogen, and oxygen (e.g. glucose (C6H12O6)).

Cells: The Fundamental Units of Life Cells are the basic structural and functional units of all forms of life. Prokaryotic cells (bacteria) lack a distinct nucleus. Eukaryotic cells (plants and animals) have a distinct nucleus. Figure 2-6

Macromolecules, DNA, Genes and Chromosomes Large, complex organic molecules (macromolecules) make up the basic molecular units found in living organisms. Complex carbohydrates Proteins Nucleic acids Lipids Figure 2-7

ENERGY Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion heat, electromagnetic radiation Potential energy – stored for possible use batteries, glucose molecules

Electromagnetic Spectrum Many different forms of electromagnetic radiation exist, each having a different wavelength and energy content. Figure 2-11

Electromagnetic Spectrum Organisms vary in their ability to sense different parts of the spectrum. Figure 2-12

Source of Energy Energy Tasks Relative Energy Quality (usefulness) Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Figure 2.13 Natural capital: categories of the qualities of different sources of energy. High-quality energy is concentrated and has great ability to perform useful work. Low-quality energy is dispersed and has little ability to do useful work. To avoid unnecessary energy waste, you should match the quality of an energy source with the quality of energy needed to perform a task. Dispersed geothermal energy Low-temperature heat (100°C or lower) Low-temperature heat (100°C or less) for space heating Fig. 2-13, p. 44

ENERGY LAWS: TWO RULES WE CANNOT BREAK The first law of thermodynamics: we cannot create or destroy energy. We can change energy from one form to another. The second law of thermodynamics: energy quality always decreases. When energy changes from one form to another, it is always degraded to a more dispersed form, and energy transfers release heat. Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form. Entropy : lack of order or predictability; gradual decline into disorder.

Practice Test Question: The Second Law of Thermodynamics is about the quality of energy. It states that as energy is transferred or transformed, more and more of it is wasted. The Second Law also states that there is a natural tendency of any isolated system to degenerate into a more disordered state.  Which of the following statements does not apply to the second law of energy (thermodynamics)? a. energy conversions results in a lower-quality energy b. energy can neither be created not destroyed c. energy conversion results in more-dispersed energy d. heat is usually given off from energy conversions

Mechanical energy (moving, thinking, living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Figure 2.14 The second law of thermodynamics in action in living systems. Each time energy changes from one form to another, some of the initial input of high-quality energy is degraded, usually to low-quality heat that is dispersed into the environment. Fig. 2-14, p. 45

SUSTAINABILITY AND MATTER AND ENERGY LAWS Unsustainable High-Throughput Economies: Working in Straight Lines Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15

Sustainable Low-Throughput Economies: Learning from Nature Matter-Recycling-and-Reuse Economies: Working in Circles Mimics nature by recycling and reusing, thus reducing pollutants and waste. It is not sustainable for growing populations.

Sustainable low-waste economy Matter Feedback Energy Feedback Inputs (from environment) System Throughputs Outputs (into environment) Energy conservation Low-quality Energy (heat) Energy Sustainable low-waste economy Waste and pollution Waste and pollution Pollution control Matter Recycle and reuse Figure 2.16 Solutions: lessons from nature. A low-throughput economy, based on energy flow and matter recycling, works with nature to reduce the throughput of matter and energy resources (items shown in green). This is done by (1) reusing and recycling most nonrenewable matter resources, (2) using renewable resources no faster than they are replenished, (3) using matter and energy resources efficiently, (4) reducing unnecessary consumption, (5) emphasizing pollution prevention and waste reduction, and (6) controlling population growth. Matter Feedback Energy Feedback Fig. 2-16, p. 47

MODELS AND BEHAVIOR OF SYSTEMS Usefulness of models Complex systems are predicted by developing a model of its inputs, throughputs (flows), and outputs of matter, energy and information. Models are simplifications of “real-life”. Models can be used to predict if-then scenarios.

Systems In open systems exchanges of matter or energy occur across system boundaries. In a closed system matter and energy exchanges across systems do not occur.

Feedback Loops: How Systems Respond to Change Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing. Positive feedback loop causes a system to change further in the same direction (e.g. erosion) Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. seeking shade from sun to reduce stress). Steady state- where inputs equal outputs so that the system is not changing over time.

Feedback Loops: Negative feedback can take so long that a system reaches a threshold and changes. Prolonged delays may prevent a negative feedback loop from occurring. Processes and feedbacks in a system can (synergistically) interact to amplify the results. E.g. smoking exacerbates the effect of asbestos exposure on lung cancer.

Practice Test Question A positive feedback loop is illustrated by all of the following EXCEPT. a. compound interest in a savings account b. exponential population growth c. a thermostat d. the greenhouse effect

Systems Natural systems do change over time what we have to figure out is what is natural and what is not and how will those changes affect us.