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Back to Electrons . . .
Planetary Model of the Atom:Central Nucleus
with protons & neutronsElectrons in orbits
SchrödingerMathematical Solution to Electron Probability
Spherical orbitals
The Hydrogen AtomOne Electron but
Multiple electron shellsGround State: level closest to nucleus
Organizing Electrons in Shells
Helium with 2 electrons?
Both are placed in Shell #1
Maximum # electrons/shell: 2n2
Atoms with More electrons
Lithium with 3 electronsExtra electron goes into next shell
Shell Organization
n = 1
n = 2
2 e
8 e
The Periodic Table
Johann Dobereiner 1817
TRIADS:Li, Na, K
Mendeleev & Meyer
1868/9Both published versions of a periodic table
of the elements
Mendeleev’s VersionLeft BLANK SPACES
For undiscovered elements:e.g. Germanium
1886
The Modern Periodic Table
Periodicity
Coinage Metals
Noble GasesChemically inert
All gasesProgressively heavier
Electron ConfigurationLi 3 electrons 2 + 1 Valence
Be 4 electrons 2 + 2 Valence
B 5 electrons 2 + 3 Valence
C 6 electrons 2 + 4 Valence
N 7 electrons 2 + 5 Valence
O 8 electrons 2 + 6 Valence
F 9 electrons 2 + 7 Valence
Ne 10 electrons 2 + 8 (filled shell)
Na 11 electrons 2 + 8 + 1 Valence
Periodicity
Ionization EnergySome atoms lose electrons more easily than others
L i Li+ + e-
Cs Cs+ + e-
Periodicity
Electron AffinitySome atoms attract electrons more avidly
Cl + e- Cl-
F + e- F-
How do Atoms Combine?
Ions = Electrically Charged Atoms
Na+ + Cl- NaCl
Salts
•Always contain balanced +/- charges•Lots of possibilities:
Li+Br- Rb+I-
K+F-
Salts
Alkaline Earth atoms & Chalcogens:
Be Be2+ + 2e-
• O + 2e- O2-
• Be2+ + O2- BeO
Bromellite
Salts
Combinations:
Opposite charges must be balanced:
Ba2+ + 2 I- BaI2
2 Rb+ + Se2- --> Rb2Se
What about Carbon?
Carbon has 4 valence electronsIt needs to lose or gain 4 electrons
to achieve Ne electron configuration
Covalent Bonding
Electron “sharing”Electrons are always paired
Atoms seek to achieve an OCTET
Water
H2O = 2 hydrogen and one Oxygen atom
Methane CH4
Carbon = 4 valence electronsHydrogen = 1 valence electron
Ammonia NH3
Nitrogen = 5 valence electronsHydrogen = 1 valence electron
Multiple Covalent Bonds
Shorter and Stronger than single bonds
Carbon Monoxide CO
Water
H2O = 2 hydrogen and one Oxygen atom
Polar Covalent Molecules
DNA’s Hydrogen Bonds
Weak bondsEasily broken but easily reformed
Chlorofluorocarbons (CFC’s)
Synthetic compoundsGood heat transfer agents
Refrigerants; aerosol sprays
Ozone Hole
Ozone = O3Absorbs ultraviolet rays Increase in skin cancer,
& cataracts
Carbon – Chlorine Bonds
Why Antarctica?
•Coldest place on earth
•Polar vortex traps gases
•Ice crystals enhance
reaction
Types 0f Chemical Bonds
Ionic Bonding Covalent Bonding
Salts; electrons lost from oneAtom and gained by anotheratom
Electrons are shared in single (one pair), double (two pairs) or triple (three pairs) bonds.
Metallic Bonding
Loosely held electronsGood conductorsTough materials
Atoms -> Molecules -> Substances
Gases Liquids Solids
Atoms far apartNon-interactiveFast movingNo shapeFormed by liquid evaporation
Atoms closerSome interactionOccupies a defined volumeSolids meltGases condense
Atoms in set arrangementAtoms vibrate but do not translateRigid ShapeStrong interactionLiquid freezes
Crystalline Solids: Carbon
Diamond Graphite
High melting pointExceptional hardness
Lubricating (slippery)
SolidsCrystalline Amorphous
Regular repeating arrangement of atoms
Lacks a regular 3-D pattern
Liquid Crystals
Minerals
Naturally occurring crystalline compound
with a known elemental composition
Silicates (SiO4) Non-silicates
Quartz pyrite
How are minerals formed?
Earth’s Interior
Inner Core: solid nickel/ironOuter Core: liquid
Mantle: SilicatesCrust: thin, rigid
Continental DriftAlfred Wegener
1880 - 1930
Meteorologist
1915 “The Origin of Continents and Oceans”
Pangaea
Plate Tectonics
Evidence:
Mesosaurus fossils
Glossopteris ferns
“puzzle pieces”
Glacial debris
Tectonic Plates
Plate Boundary TypesDivergent Convergent Lateral
Transform
North American and Eurasian plates
Nazca and South American plates
San Andreas fault
Finding the epicenter
Richter ScaleLogarithmic
scale
7.2 quake hasamplitude
10x greater than6.2
30x energy released
The Ring of Fire
Hot Spots
Volcanic Eruptions
Krakatoa 1883
Volcanic Eruptions
Kilauea
Mt St Helens (1980)
Before and after the May 1980 eruption
Mt Redoubt
Alaska 2009
Mt Tambora (1815)
1816
The Year without a Summer
““Darkness” (Lord Byron)
“I had a dream, which was not all a dream.The bright sun was extinguish'd, and the stars
Did wander darkling in the eternal space,Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air;Morn came and went--and came, and brought no day”
Volcanoes & Climate
1783/1784:Laki, Iceland
Asama, Japan
Earth’s Atmosphere
Shell of gases circling the Earth
Troposphere
Where all weather systems operate
Densest layer, due to gravity
Stratosphere
Ozone LayerJet stream
IonospherePropagates AM radio signals
(Longer wavelengths)Aurora Borealis (Northern Lights)
Early Earth’s Climate
3 Billion years agoinitially H2 & He
Nitrogen (N2),
Carbon dioxide(CO2)
from volcanoes
PhotosynthesisCO2 + H2O -----> O2 + Glucose
Earth’s current atmosphereN2 78%
O2 20.9%
Ar 0.93 %
CO2 0.038%
Carbon Dioxide Levels
Humidity
Hydrological Cycle
Water Molecules in Air
Volume increases with higher temperatureDensity decreases with temperature
HOT AIR RISES and HOLDS MORE H2O9 g @ 10°C 17 g @ 20°C
30 g @ 30°C
Relative Humidity
Amount of water vapor increasesEXPONENTIALLY With temperature
Saturation Pointmaximum amount of H2O vapor at that temperature
Reached by 1. Excessive evaporation
2. Rapid Temperature drop
Dew
Water condenses as Temperature drops
Night temperatures cooler
FrostIs formed if temperature
approach the freezing point of H2O
(32°F or 0°C)
SF Bay Fog
Cooler ocean air + warm land
Usually late afternoon
Clouds
Weather Systems
Warm front
Ring around the Sun (or Moon)
Means rain on the way
Weather Systems
Cold front
Thunderstorms
Lightning = Voltage Discharge
Hail
Severe Weather
Tornadoes and WaterspoutsWind speeds 60 – 120 mph
Tornado Formation
Tornado Frequency
Tornado Season
Cyclonic Storms
Hurricanes & Typhoons
Hurricane Formation
Warm ocean waters temperatures > 76°F
> 24.4°C
Hurricanes 2005
26 stormsJune -> December
El Nino1997 – 1998 winter
Flooding in N. & S. AmericaRecent drought & fires in Asia
El Nino Southern Oscillation (ENSO)
1982 – 1983 winter
El Nino/La Nina Events
Earth’s climate
The Last Million Years
Climate cycles:Hot House vs. Ice Age
Average: 15° C
The Last Ice Age
Climate Cycles
Orbital variation
Tilt change
Solar flux
Orbital Variations
100,000 year cycles
Obliquity of the Earth’s Axis
Change in the Earth’s Tilt
41,000 year cycle
Greater tilt: Interglacial
Less tilt: Glaciation
Precession26,000 year cycle
Changes in Solar Flux
Sunspots?
25 April 2009
Maunder Minimum
Historic Climate Eras
Medieval Warm PeriodPopulation Boom
Viking Travel
England exported wine
Steppe Drought
The Little Ice AgeGrain production
Ergot Blight
Plague
Patagonianicefields
Climate Cycles
Role Of
CO2
Greenhouse Gases
Greenhouse Gases
Svante Arrhenius
Fuel Burning <-> Global Warming
cutting the amount of CO2 in the atmosphere by half could lower the temperature in Europe by some 4-5 oC.
Greenhouse Gases Sources
CxHyOz + O2 -> CO2 + H2O
Greenhouse Gases
Greenhouse Gas Levels
Venus
800 K temp
90x atmosphere
96% CO2
Global WarmingGlacial Melting
Permafrost thaw
Increased evaporation
Seasonal change
Coral reef bleaching
Glacial Melting
Arctic Ice Cap
Greenland Ice
Antarctic Ice
Sea Level Rising
Imperiled Coastlines
One – Five Meter Sea Level Rise
Consequences
Local Consequences
Increased Evaporation RatesSevere Storms
Coastal Erosion
Fires
Tropical Storm Formation
2005
KatrinaRita
Wilma
Coastal Erosion
Saltwater Intrusion
More Frequent El Niño
1997-8 El Niño
El Niño Frequency
Permafrost Thaw
Coral Reef Bleaching
Wildlife Habitats
Already Extinct
Expanded Pest Ranges
More Pests
Physical ScienceThe Universe Around Us
How does it Work?
What is it made of?
How does it affect us?
Physical ScienceThe Universe Around Us
How does it Work?
What is it made of?
How does it affect us?
How have we affected the world?