What is geochemistry?
Why do elements in the same group on the periodic table have similar properties?
Why are inert gasses stable?
Why do elements form bonds?
How do we obtain information about elemental abundance in the
universe?
What are the two most abundant elements?
How is elemental abundance related to atomic number? to whether the
atomic number is odd or even?
Which elements have unusually low abundance?
Which have unusually high abundance?
Suggest reasons for these anomalies.
How are heavy elements formed?
What determines the present composition of the sun?
What are the three main types of meteorites? What are their compositions?
What are the subclasses of stony meteorites?
What is a chondrule? Of what substances are chondrules composed?
What is a carbonaceous chrondrite?
Why are carbonaceous chondrites considered especially important?
What is the probably composition of the Earth's core?
What evidence supports this conclusion?
What is the probable composition of the Earth's mantle?
Evidence?
Is the upper mantle believed to be the same composition as the lower
mantle?
What elements are the most abundant in the Earth? in the Earth's crust?
What similarities and differences are there in the compositions of the Earth and meteorites?
How is the average composition of the Earth's crust obtained?
How does the composition of the continents differ from that of the
ocean floors?
What are siderophile elements? chalcophile elements? lithophile
elements? atmophile elements?
Where did these terms come from?
Are the concepts embodied in Goldschmidt's geochemical classification
of the elements valid? Explain.
Outline the history of the Earth, including the following:
Is continental crust generation a one-way or cyclical process?
What evidence is obtained from:
What is the significance of the following?
What is the present composition of the atmosphere?
How did the atmosphere originate? Evidence?
What atmospheric changes have occurred? Evidence?
What is the present composition of seawater?
How did the ocean originate?
What changes have occurred in oceanic composition? Evidence?
What would happen if the amount of Ca+2 in the ocean
decreased? increased?
if the amount of Mg+ increased? decreased?
How does the composition of the Moon differ from that of the
Earth?
What common Earth minerals have not been found on the Moon? Suggest
reasons for their absence.
What is the main compositional difference among the planets?
What kinds of rocks are known or suspected to exist on the following:
What is geochronology?
What is radioactivity? What changes take place during radioactive
decay?
Define half life, parent element, daughter element.
What assumptions are routinely made in radiometric dating procedures?
What are isochrons? How are they obtained?
How can Rb, Sr dating and K, Ar dating be used to determine age of metamorphism?
How can Rb, Sr be used to determine crustal vs. mantle origin of rocks?
How can the 87Sr/86Sr ratio be determined for current mantle rock? for older mantle rock?
In a 238U -> 206Pb study, the original ratio of 206Pb/204Pb must be known. How can this be determined?
What are concordant ages? discordant ages?
What is a concordia curve? How can one be used in radiometric dating?
What is the lead-lead method? Why is it particularly useful?
How can 238U -> 4He be used to determine
solidification ages?
Where has this method been used? What problems are there with this
method?
How are U and/or Pb used to determine the following:
Explain how fission track dating is done.
List some advantages in using K, Ar for radiometric dating, list some disadvantages.
Discuss the use of 14C in radiometric dating.
What is fractionation?
How can it be produced by physical processes? by chemical processes?
by biological processes?
How can the temperature be determined that prevailed when a certain
process was occurring?
What is a factionation factor?
What standards are used for comparing isotopic separations of O, H,
C, and S?
What are delta values? In what units are delta values
expressed?
Why are delta values more useful than fractionation factors?
Give examples of how each of the following stable isotopes might
be used by geologists:
1H/2H, 12C/13C,
16O/18O, 32S/34S.
What do we mean by saying that a chemical system is in equilibrium?
State LeChatelier's Principle and give an example to illustrate the principle.
What is an equilibrium constant?
Write an expression involving concentrations which may be used to
obtain the equilibrium constant for a chemical reaction.
What are "standard" concentrations for aqueous solutions? for
gases? for solids? for pure liquids?
What are "standard" temperatures and pressures?
Be able to work problems dealing with equilibrium constants. (Examples: determining K if equilibrium conditions are given, determining concentrations of some compounds if other compounds' concentrations are given, etc.)
Why are many natural systems not in equilibrium?
What agents are most significant in chemical weathering processes?
What is a solubility product?
What is the common ion effect? What does it do to solubility?
Given solubility products and the appropriate chemical reactions, be able to determine solubilities of salts and gases in pure water, and in solutions which already contain "common" ions.
What effect does temperature have on solubility?
Give 4 reasons why real solubilities of compounds are not the same as theoretically calculated values.
Define pH.
What is a neutral solution?
What is a buffered solution? Give an example.
Consider the reaction which represents the
dissolving/precipitation of CaCO3.
Discuss in detail the effect of each of the following on this
reaction:
How can we detemine whether one carbonate will replace another?
What is the "dolomite problem" and what is the most commonly accepted explanation for this problem?
Define:
How can a colloidal suspension be distinguished from a true solution? from a suspension?
What is the Tyndall effect?
What are Liesegang rings?
Why do colloids possess electrical charges?
How can one cause a colloid to "flocculate?"
What is ion exchange?
What determines the ease with which ion exchange can occur?
List some of the things which have been used as geologic evidence that a given deposit is colloidal in origin.
How are the clay minerals formed (discuss overall reaction and possible reaction mechanisms)?
What geologic conditions favor formation of each of the major types of clay minerals?
What are laterites?
How does the composition of laterites differ from that of temperate
zone soils?
Give an explanation of this composition difference.
Define:
Give equations which may be used to determine Eh for non-standard concentrations and for non-standard temperatures if standard oxidation potentials are known.
Very important! Be able to use simple Eh-pH diagrams to determine mineral stabilities.
Be able to discuss (with appropriate equations) hydration reactions for the following minerals:
For each of the following substances: quartz, iron compounds, carbonates, aluminosilicates
Define and know symbols where appropriate:
Be able to state the first and second laws of thermodynamics, in words and mathematically.
Be able to calculate enthalpy changes for reactions if the heats of formation are given for the compounds involved in the reaction.
What is the significance of a reaction's having a negative free energy change? a large free energy change? a small free energy change? no free energy change?
What do we mean by the terms fugacity and activity?
Why are these concepts useful in geology?
How are fugacities and activities of different substances determined?
What geochemical evidence favors the "asteroid" theory of dinosaur
extinction?
What geochemical evidence opposes the theory?