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Molecules
combinations of two or more atoms (N2, CO2, NaCI, H2O)
Atoms held together by bonds (strongest to weakest):
• Covalent bond • Ionic bond • Hydrogen bond
Covalent bond
atoms share electrons (CO2)
Ionic bond
atoms bound by electrical attraction (NaCI = Na+ + CI-)
Hydrogen bond
“partial ionic bond” between molecules
Describe a water compound
Partial charges at opposite ends of molecule “Polar” molecule
High heat capacity
measure of amount of heat energy that must be absorbed by the substance to raise the temperature 1 degree C
Concentrations of H+ (protons) and OH- (electrons) determine pH in an ________ solution.
aqueous
The solution is acidic if
H+ (protons) concentration greater than OH- (electrons)
The solution is basic if
OH- (electrons) concentration is greater than H+ (protons)
T or F: only an acidic solution can be lethal.
F: Both an acidic and basic solution can be lethal
What are examples of high/basic pH?
NaOH (sodium hydroxide), ammonia, seawater
What are examples of low/acidic pH?
acid rain, stomach acid, lemon juice, car battery acid
What are examples of neutral pH?
pure water
What elements are important for soil health and plant growth?
calcium, phosphorus, potassium, sulfur, nitrogen, magnesium
What are the effects of a basic soil?
nutrients (e.g., P, Mg) not soluble (unavailable to plants)
Dark leaves indicates _________ limitation/deficiency
phosphorus
What are the effects of an acidic soil?
toxic metal ions (e.g., Al) more available/soluble
As pH drops/Al availability increases, plants
grow slower
Atoms
elemental units (“building blocks of matter”)
Isotopes
Same number of protons, but different numbers of neutrons
What are the two isotopes of hydrogen?
• Deuterium • Tritium
Deuterium
stable isotope (not radioactive; does not disappear)
Tritium
radioisotope (radioactive, spontaneous decay occurs)