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Chapter 2

Chapter 2- Matter, Energy, and the Physcial Environment.docx

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Department
Environment
Course
ENV100Y5
Professor
Monika Havelka
Semester
Fall

Description
September 16, 2013 Chapter 2- Matter, Energy, and the Physical Environment Matter  Matter- Any material that has mass and occupies space  Law of conservation of matter: Matter may be transformed from one type of substance into others, but it cannot be created or destroyed Chemical Building Blocks  Elements- A fundamental type of matter; a chemical substance with a given set of properties, which cannot be broken down into substances with other properties  Atoms- The smallest component of an element that maintains the chemical properties of that element which consists of:  Protons: positively charged particles  Neutrons: No electric charge  Electrons: negatively charged particles  Atomic Number: atoms of each element have defined number of protons  Isotopes- One of several forms of an element having differing numbers of neutrons in the nucleus of its atoms  Some isotopes are radioactive which decay into lighter radioisotopes until they become stable isotopes and the rater of decay is determined by its half-life: the amount of time it takes for half the atoms to give off radiation and decay  Ions- An electrically charged atom or combination of atoms  Cations: Ions that form when an atom loses electrons, and thus, carry a positive charge  Anions: Ions that form when an atom gains electrons, and thus, carry a negative charge Molecules and Compounds  Molecules- A combination of two or more atoms  Compound- A molecule whose atoms are composed of two or more elements  Bond- A chemical-physical connection between two or more atoms; an electrical force linking two atoms together  Covalent Bonds- when atoms in a molecule share electrons (sometimes unequally)  Ionic Bonds- oppositely charged ions formed when an electron transfers from one atom to another  Solution- A chemical mixture Water Molecule  Oxygen atom in water molecule attracts electrons more strongly than the two hydrogen atoms, resulting in polar molecule in which oxygen has negative charge & hydrogen has positive charge  Hydrogen Bond: Oxygen atom of one water molecule is weakly attracted to hydrogen atoms of another  Properties of Water molecule that support life:  Liquid over a wide range of temperature  Water based processes occur in a variety of conditions  Strong cohesion  Water molecules are polar (universal solvent) – Facilitates bonding with other chemicals  Facilitates the transport of chemicals  High heat capacity  Stabilizes systems against change September 16, 2013  Solid less dense than liquid – Floating ice insulates water  Transparent to light  Photosynthesis is possible Hydrogen Ions Control Acidity  In any aqueous solution (a solution in which water is present as a solvent), a small number of water molecules dissociate/split apart, each forming a hydrogen ion (H+) and a hydroxide ion (OH-)  PH Scale- A measure of concentration of hydrogen ions in a solution  Acidic: H+ concentration > OH-  Basic: OH- > H+ Organic and Inorganic Compounds  Organic (presence of carbon) Compounds- A compound made up of carbon atoms joined by covalent bounding and sometimes including other elements  Hydrocarbons- An organic compound consisting solely of hydrogen and carbon atoms o Methane- The simplest hydrocarbon compound o Some hydrocarbons pose health hazards to wildlife and people  Inorganic Compounds- Chemical compounds that are of mineral origin and may contain carbon (characterizes organic compounds) but lack the carbon Macromolecules Are Building Blocks of Life  Polymers- Combination of organic compounds to form long chains of repeated molecules and three types essential to life include:  Proteins- A large molecule made up of long chains of amino acids  Nucleic Acids- A molecule that directs the production of proteins o Deoxyribonucleic Acid (DNA)  Genes- Regions of DNA coding for particular proteins that perform particular functions o Ribonucleic Acid (RNA)  Carbohydrates- An organic compound consisting of atoms of carbon, hydrogen, and oxygen (Glucose)  Lipids (not polymers)- One of a chemically diverse group of large, biologically important molecules that are classified together because they do not dissolve in water  Plastics- A synthetic polymer material, derived from the hydrocarbons in petroleum (human made polymers) Energy  Energy- An intangible phenomenon that can change the position, physical composition, or temperature of matter and consists of two types: 1. Potential Energy- Energy of position  Chemical energy- energy held in the bonds between atoms  Nuclear Energy- the energy that holds atomic nuclei together and is released when an atom is split  Mechanical energy- the energy in a compressed spring 2. Kinetic Energy- Energy of motion (thermal, light, electrical, sound energy, etc) Energy is Always Conserved but can Change in Quality  The first law of thermodynamics- the total energy in the universe remains constant and thus is said to be conserved September 16, 2013  The second law of thermodynamics- the nature of the energy will change from a more ordered state to a less ordered state, if no force counteracts this tendency Light Energy from the Sun  Autotrophs/Primary Producers- An organism that can use the energy from sunlight to produce its own food; green plants, algae, etc  Photosynthesis- The process by which autotrophs produce their own food; sunlight powers a series of chemical reactions that convert carbon dioxide and water into sugar (glucose) transforming low quality energy from the sun into high quality energy the organism can use  Consumers/Heterotrophs- An organism that consumes other organisms; animals, fungi, etc  Cellular Respiration- The process why which a cell uses the chemical reactivity of oxygen to split glucose into its constituent parts, water and carbon dioxide, and release chemical energy that can be used to form chemical bonds or to perform other tasks within the cell Geothermal Energy  Geothermal Energy- Renewable energy derived from heat generated deep within earth; radioactive decay of elements at depth generated heat that rises to the surface in magma, through heat flow by conduction, and through fissures and cracks  Chemosynthesis- The process by which bacteria in hydrothermal vents use the chemical energy of hydrogen sulphide to transform inorganic carbon into organic compounds Geological Systems: The Physical Basis for the Environment  Age of sun and solar system: 4.57Ga (billion years)  Based on models of stellar evolution and dating of primitive solar system objects  Age of Earth: 4.54 Ga  Based on ages of terrestrial rocks + age of solar system + models of solar system formation The nebular theory explains the origin of the solar system  Interstellar cloud inherits elements from previous generation of stars  Rotation  Gravitational collapse  Solar nebula is formed The Solar System  Jovian (outer) planets are huge, gaseous, and icy  Terrestrial (inner) planets are small, rocky, and metallic  Nebular theory  Interstellar cloud of gas and dust  Rotation, gravitational collapse September 16, 2013  Solar nebula  Nuclear fusion in the sun  Condensation  Accretion  Differentiation Early earth was a different place- 4.5Ga earth was a hostile place  Constant volcanic activity  Meteorite impact bombardment  Intense ultraviolet radiation from the sun  No liquid water (Evaporated since it was so hot)  No life existed  Radioactive decay in Earth’s core created active Atmosphere  The atmosphere and hydrosphere have changed over time, the early atmosphere:  Primitive vs secondary atmosphere  Role of volcanic degassing  Earth’s early atmosphere was: o Reducing (oxygen poor) o Dense (high atmospheric pressure) o Rich in greenhouse gases o Hot o Not hospitable for life as we know it  Atmosphere-hydrosphere-geosphere interacted dynamically  Surface cooled enough to sustain liquid water  Still hot- water precipitated and re-evaporated o Water + atmospheric gases > acids > weathering of minerals Life’s Origin  Several hypothesis have been proposed to explain life’s origin  Heterotrophic hypothesis (primordial soup) o Life originated from inorganic chemics in the ocean o First life forms used organic compounds for energy o 1953 primordial soup experiments:  Tested the hypothesis that conditions on the early earth were conductive to producing the building blocks of life  Tries to recreate early earth conditions  Made all 20 amino acids, sugars, lipids, pyr
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