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Where do we start?–Create the Universe–Form the Earth and elements–move the elements into their

correct positions–build the atmosphere and oceans

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The BIG BANG

• The Universe was created 15 billion years ago in one BIG BANG ...... How do we know?

• Start with the atom

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ENERGY

Nucleus

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ENERGY

Nucleus

} E = hv

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Elemental Absorption

• Every element has a characteristic absorption spectra - (ICP)

Wavelength400 nm 700 nm

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http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T014334A.gif

Spectrum of the Sun

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• From the magnitude of the shift we can calculate the speed of the star.

• The more distant stars are moving the fastest.

• From distance and velocity information -> TIME 15 billion years!

Wavelength

400 nm

700 nm

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At the Start

Big Blob of Neutrons (N)

Protons and

electrons

BANG

12 Minutes

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Now we are COOKING ........... Fusion produces heat

E = mc2

1 gram of hydrogen will produce 6.3x1011 j of heat.Enough heat to boil 2 million liters of H2OCompare this to our terrestrial energy consumption.

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C

CH217: King 12• This process stops at iron-56

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Elements H-1 through Fe-56

Supernovae

Explosion

Second Generation Star

H through Fe and n

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Elements H-1 through Fe-56

Supernovae

Explosion

Second Generation Star

H through Fe and n

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5

6

7

8

6 7 8 9

Prot

on N

umbe

r

Neutron Number

14C

14Ne-

Beta Decay

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17

18

19

20

20 21 22 23

Prot

on N

umbe

r

Neutron Number

40K

40Ar

e-

Electron Capture

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143

144

145

146

147

89 90 91 92 93

Prot

on N

umbe

r

Neutron Number

234Th

238U

4He

Alpha Decay

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Review of Element Formation

• Big Bang• Nuclear “Cooking” - Fusion• Neutron Capture• What is the end result?

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What about the Earth?

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Another look at the earth on a linear scale.

• Where did all the other elements go? H, He, C, N??They got BLOWN AWAY

This leaves just Si, Mg, Fe, and O

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.....and just for fun

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Formation of the Earth• The earth started as a hot molten blob of metal and

oxygen• As the blob cooled, density differences of the

original components drove an elemental segregation.

• Metallic iron - The Earth’s core• Mg, Fe, and Si oxides - The crust• How do we know?• We know from earthquake seismology

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A Slice of the Earth

Inner Core

Outer Core

Mantle

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A Slice of the Earth

Inner Core

Outer Core

Mantle

2900 km

• earthquakes travel as shear waves or compressional waves

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• shear waves only pass through SOLIDS (mantle)• So we have a “liquid” iron core. This has important

implications for other elements– Ni, S, Au, Pt, Ag, Pb dissolve in the liquid iron

• What is left is Mg, Si oxide mantle.• The mantle is not really solid, but really a “putty”

that is kept warm by the radioactive decay of 40K, 235U, 238U, and 232Th.

• The heating of the mantle drives convection cells.

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Inner Core

Outer Core

Lower Mantle

Crust

• The mantle melt cycle (subduction/formation) enriches the crust further in Si, Na, K, Ca, and Al

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What about the Oceans and the Atmosphere?

• The Earth is about 0.5% water. Where did it come from?

• The source of water in the early Earth is poorly understood ...we are lucky that it arrived.

• The gravitational attraction of the Earth retained almost all of the water.

• Surface water puts important constraints on global temperature! 0 <--> 100 oC.

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Controls on CO2• CO2 is controlled by a global scale feedback loop

with a time scale of >10,000 years• Consider the following reactions:

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Controls on CO2• CO2 is controlled by a global scale feedback loop

with a time scale of >10,000 years• Consider the following reactions:

Generic Weathering Reaction

Generic Precipitation Reactions

Generic Mantle Reactions

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AtmosphereAtmosphere

ContinentalContinentalCrustCrust

OceanicOceanicCrustCrust

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Lets work with units

CO2 (g) 0.0365 %, This is a mixing ratio

O2 20.95%

N2 78.08%

Ar 0.93%

PV= nRT, average mass gas 28.96 g/mol

%, 00/0, ppm, ppb

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PressureAtmospheric Pressure is a force: kg/m2

P0 = Mass(atm g)/4(r2

r = 6.37x106 m P0 = 101325 Pa

Ph = Po e -Mgh/RT

M = 0.029 kg/mol

R = 8.314 J/mol K

g = 9.81 m/s2

Scale height 5-6 km

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Unit Conversion