Chapter 2 Topics:  The fundamentals of matter and chemistry  Energy, energy flow, energy in Earth’s systems  Geology: plate tectonics and the rock cycle  Geologic and natural hazards and ways to mitigate them

Chemistry  Chemistry: studies types of matter and their interactions  Chemistry is crucial for understanding:  How gases contribute to global climate change  How pollutants cause acid rain  Environmental health impacts to wildlife and people  Water pollution and wastewater treatment  Atmospheric ozone depletion  Energy issues

Matter is conserved  Matter = all material in the universe that has mass and occupies space  The law of conservation of matter: matter can be transformed from one type of substance into others  But it cannot be destroyed or created  Because the amount of matter stays constant  It is recycled in nutrient cycles and ecosystems  We cannot simply wish pollution and waste away

Atoms and elements  Element = a fundamental type of matter with a specific set of physical and chemical properties  Atoms = the smallest components that maintain an element’s chemical properties  The atom’s nucleus is composed of protons (positive charge) and neutrons (no charge).  Atomic number = the number of protons  Electrons = negatively charged particles at different energy levels surrounding the nucleus

The structure of an atom

Isotopes – variation on a theme  Isotopes = atoms of the same element with different numbers of neutrons  Isotopes of an element behave differently  Mass number = the combined number of protons and neutrons

Radioactive decay of isotopes  Radioactive isotopes decay becoming stable isotopes  Half-life = the time for one-half of the atoms to decay  Half-lives range from fractions of a second to billions of years

Bonds hold atoms together  The configuration of electrons controls how atoms become bonded with each other  Bonds in elements (same kind of atoms)  Metallic – electrons are shared among all atoms  Covalent – electrons are shared with one other atom  Bonds in compounds (different kinds of atoms)  Covalent – electrons are shared with a fixed number of atoms (molecule = smallest piece of covalent material)  Ionic – electrons are given/taken, creating electrically charged atoms called “ions”

Water’s chemistry is unique  Water has “polar” molecules that link with hydrogen bonds  Water has strong cohesion and adhesion (capillary action and good solvent)  Water has a high heat capacity (storing and releasing thermal energy with only small changes in temperature)

Hydrogen ions determine acidity  pH indicates the acidity of solutions  Acidic: pH < 7  Basic: pH > 7  The pH scale is logarithmic: a pH of 6 reporesents10 times as many H + as a pH of 7

Carbon chemistry is diverse  Carbon has the ability to form covalent bonds with up to four other atoms  Compounds containing covalently bonded carbon are called “organic” compounds  Hydrocarbons are composed only of carbon and hydrogen

The building blocks of life  Four types of macro- molecules have key roles in all living things:  Proteins  Nucleic acids  Carbohydrates  Lipids

Proteins  Long chains composed of amino acids  Produce tissues, provide structural support, store energy, transport material  Animals use proteins to generate skin, hair, muscles, and tendons  Some are components of the immune system or hormones  They can serve as enzymes = molecules that promote chemical reactions

Nucleic acids  Long chains of nucleotides that contain sugar, phosphate, and a nitrogen base  Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) carry hereditary information of organisms

Carbohydrates  Compounds of carbon, hydrogen, and oxygen  Sugars are simple carbohydrates of 3–7 carbons  Glucose = C 6 H 12 O 6 – provides energy for cells  Complex carbohydrates store energy and build structures  Starch = stores energy in plants  Chitin = forms shells of insects and crustaceans  Cellulose = provides structure in cell walls of plants  Lignin = provides structure (woody tissue) in vascular plants

Lipids  Complex organic compounds that include fats, waxes, and fatty acids  Store energy, provide signaling, form cell membranes  Commonly hydrophilic on one end and hydrophobic on the other

Energy – the ability to do work  Kinetic energy – the energy of motion  Electromagnetic Light  Electrical Electrons  Thermal Individual atoms  Mechanical Groups of atoms  Potential energy – stored energy  Nuclear In atomic nuclei  Chemical In chemical bonds  Elastic In stressed materials  Gravitational In position relative to other matter

Thermodynamics  First law of thermodynamics = energy can change forms, but cannot be created or destroyed  Energy efficiency = the proportion of useful energy obtained from an energy conversion  Second law of thermodynamics = energy changes from a more-ordered to a less-ordered state  Entropy = an increasing state of disorder  Adding energy from outside a system can increase its order

Source characteristic  Energy density  Most natural sources of energy supply vast amounts of energy, but do so in a very diffuse way  Fossil fuels have very high energy densities  Intermittency  Most natural sources of energy are kinetic and can be intermittent  Fossil fuels contain potential energy and can be used continually

Energy in Earth’s systems  Energy from the sun drives three of Earth’s four systems  Atmosphere Uneven heating of Earth’s surface  Hydrosphere Evaporation of water from the ocean  Biosphere Photosynthesis  Energy from within the Earth drives the other system  Geosphere Convection in the mantle as thermal energy moves from the core to the crust

Energy in the biosphere  Autotrophs (primary producers) = organisms that produce their own food  Green plants  Algae  Cyanobacteria  Heterotrophs = organisms that gain energy by feeding on others  Animals  Fungi  Microbes

Capturing energy - photosynthesis  Chloroplasts contain chlorophyll, a light- absorbing pigment  Light reactions = split water and make ATP  Calvin cycle = links carbon atoms from carbon dioxide into sugar (glucose)

Capturing energy - chemosynthesis  Uses energy in hydrogen sulfide to produce sugar  Occurs at the bottom of the ocean along divergent plate boundaries where the lack of sun prevents photosynthesis  Hydrothermal vents = host communities that thrive in high temperature and pressure

Geology  Geology = the study of Earth’s physical features, processes, and history  Geologic processes at and below the Earth:  Shape the landscape  Influence processes in the oceans  Provide the foundation for environmental systems  Determine the distribution of mineral resources  Create natural hazards

Earth’s interior is layered  Core = solid iron/nickel (inner core), molten iron/nickel (outer core)  Mantle = dense “rocky” material, composed of iron-rich silicate minerals, plastic behavior  Crust = thin, low-density rock (continental, oceanic), brittle behavior  Lithosphere = the crust and uppermost mantle

Plate tectonics  Earth’s lithosphere consists of discrete pieces (plates) that move with respect to each other and interact along their boundaries  The process is driven by the outward movement of thermal energy from the core toward the crust  Convection within the mantle causes movement of the plates, creating and recycling Earth’s crust(s)  Continents have formed, combined, separated, and recombined over millions of years

Divergent boundaries  Oceanic-Oceanic  Mid-ocean ridges  New oceanic crust is created  Continental-Continental  Rift valleys  Continents are pulled apart

Convergent boundaries (subduction)  Oceanic crust is subducted back into the mantle  The melting slab yields an iron-poor, silica-rich magma  Oceanic crust is destroyed  Continental crust is created  Oceanic-Oceanic  Island arcs (volcanic)  Oceanic-Continental  Volcanic mountain ranges

Convergent boundaries (collision)  Continental-Continental  Folded mountain ranges  No subduction occurs  Continental crust is too light (low-density)  Continents collide and merge together  Continental crust accumulates

Transform boundaries  Lateral, side-by-side motion  Grinding, stick-slip movement stores and releases large amounts of energy

Plate tectonics affects…  Not only  The location and severity of earthquakes and volcanoes  But also  The geography of continents and oceans  Which affects the patterns of ocean currents  And influences the distribution of rainfall  Both of which affect climate  Which determines the rates of weathering and erosion  And the distribution of biomes and ecosystems

The rock cycle  The processes by which Earth’s mineral matter is recycled among  magma  igneous rock  sediments  sedimentary rock  metamorphic rock

Igneous rock  Igneous rock forms when magma/lava cools and crystallizes  Intrusive igneous rock = magma that cools slowly below Earth’s surface (e.g. granite)  Extrusive igneous rock = lava that cools quickly above Earth’s surface (e.g. basalt)

Sedimentary rock  Sedimentary rock forms when sediment (loose mineral grains) is lithified (compacted and cemented)  Clastic rock = derived from other rocks  Chemical rock = precipitate from solution

Metamorphic rock  Metamorphic rock forms when minerals in a rock change due to heat and/or pressure (no melting!!)  Occurs deep within the crust when continents collide  Shale-slate-phyllite- schist-gneiss

Geologic and natural hazards  Some consequences of plate tectonics are hazardous  “The Ring of Fire” – the circum-Pacific belt of subduction zones and fault systems  90% of earthquakes and 50% of volcanoes

Earthquakes  Earthquakes = sudden movement of the lithosphere, releasing accumulated stress  Largest earthquakes occur at convergent and transform boundaries due to compression and shear

Volcanoes  Volcano= molten rock, hot gas, or ash erupt through Earth’s surface  Greatest hazards posed by volcanoes at subduction zones due to explosive style  Also found above hot spots and at divergent boundaries

Environmental impacts of volcanoes  Ash blocks sunlight  Sulfur emissions also scatter sunlight and contribute to acid rain  Large eruptions, such as Mount Tambora’s in 1816 can decrease global temperatures “the year without a summer”

Mass wasting  Mass wasting = the downslope movement of soil and rock due to gravity  Speeds range from imperceptible “creep” to extremely rapid “lahars”  Water often plays a key role in triggering and movement

Tsunamis  Tsunami = waves created by sudden displacement of large volumes of water  Generally due to earthquakes  Extremely long wavelength produces persistent inland flow

We often make things worse  As populations grow, many people have no choice but to live in susceptible areas  But many also choose to live in attractive but vulnerable areas (beaches, mountains)  Engineered landscapes increase frequency or severity of hazards (damming rivers, suppressing fire, mining, clearing vegetation, changing slopes)  Changing climate alters rainfall patterns, increases drought, fire, flooding, storms