ENVIRSC 2Q03

Geochemistry

Geochemistry

field that takes knowledge of chemistry and applies it to understand the earth system and surrounding environments

Why are metals important?

• commonly found in chemically reduced states (early earth) → mining

• are toxic in high concentrations→ monitoring

Geogenic

not of anthropogenic origin

Lithosphere

• solid earth

• Earth’s crust, rock, and landforms

Atmosphere

• gasses (the air)

• is made up of a mixture of gasses

Hydrosphere

• all water

• bulk is the ocean (> 97%), ice caps and glaciers (< 1%)

Biosphere

• all life

• living and dead organic matter

Atom

small nucleus surrounded by cloud of moving electrons

Nucleus

composed of nucleons, which include protons and neutrons

Electrons

very small, negatively charged particles

Atomic number (Z)

number of protons in a atom

Neutron number (N)

number of neutrons in an atom

Atomic mass

• number of protons and neutrons in an atom

• normalized to C12

Isotopes

elements with same chemical properties but different masses due to having more or less neutrons

Ionic bonds

• donation of electrons

• largely controlled by charges of ions involved and their radii

• weaker in water than dry air

Covalent bonds

• sharing of electrons (orbital overlap) to get filled octet

• elements have similar electronegativity

Cations

give up electrons, are positive ions

Anions

take electrons, are negative ions

What are the polyatomic ions?

• Hydroxide

• Carbonate

• Bicarbonate

• Nitrate

• Sulphate

• Phosphate

Normality (N)

moles of charge equivalents per liter solution

Mole fraction

fraction of total moles of species of interest

Standard curve

relationship between known concentrations and detector response

Accuracy

metric to gauge how close collected data are to some true value

Precision

metric to gauge how consistent a series of measurements are relative to each other