zoology chemistry. elements and compounds chemistry = study of matter and interactions all living...
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Zoology
Chemistry
Elements and Compounds• Chemistry = study of matter and interactions
• All living thing are made of matter– Matter takes up space and has mass
Elements and Compounds
• Elements = matter that cannot be broken down into simple substances by chemical (ordinary) means
• 92 natural; ? Artificial
• 96% of all life = CHON
• Other 4% = Ca, K, S, Na, Cl, Mg
• Trace elements = minute quantities but essential to life (B, Cr, Cu, I, Fe, Mn, Sn, Zn)
Elements and Compounds• Compounds = molecules composed of 2 or more
elements chemically combined • Compounds have different properties from their
original elements
Atomic Structure/Behavior
• 2 basic parts: nucleus and electron ‘cloud’
• Nucleus = ‘center’
– Protons (+1) and neutrons (0)
– All mass is in the nucleus
• Electron ‘cloud’; electron(s)
– (-)
– Negligible mass
Structure/Behavior
• Atomic number = number of protons (+)• Atomic mass = no. protons (at. no.) + no.
neutrons– Average of isotopes found in nature– All elements have isotopes
• Carbon - 12, 13, 14
• Isotope = same atom with different atomic mass– May be unstable
• Atomic number = number of protons (+)• Atomic mass = no. protons (at. no.) + no.
neutrons– Average of isotopes found in nature– All elements have isotopes
• Carbon - 12, 13, 14
• Isotope = same atom with different atomic mass– May be unstable
Unstable Isotopes • Radioactive spontaneous decay of subatomic
particles or energy – Alpha (α), Beta (β), Gamma(γ)
• Radiation is transformation into a stable element• Radiation may be detected• Used for dating, tracers, cancer treatment (Co)
• Radioactive spontaneous decay of subatomic particles or energy
– Alpha (α), Beta (β), Gamma(γ)• Radiation is transformation into a stable element• Radiation may be detected• Used for dating, tracers, cancer treatment (Co)
Structure/Behavior
• Energy Levels: Electrons and orbitals – distance of electrons from the nucleus
• Arrangement of outer electrons determines how atoms interact with other atoms to form molecules
• Electrons in the outer shells are more reactive and cause ‘chemical changes’ ‘Chemistry’
• Energy Levels: Electrons and orbitals – distance of electrons from the nucleus
• Arrangement of outer electrons determines how atoms interact with other atoms to form molecules
• Electrons in the outer shells are more reactive and cause ‘chemical changes’ ‘Chemistry’
Chemical Bonds
• Attractions of atoms or molecules to form new compounds
• Three types:
– Covalent – electrons shared
– Ionic – electrons exchanged
– Hydrogen – attractions between molecules
Covalent Bonds
Ionic Bonds
• Atoms that have gained/lost electrons are called (?)
• Ionic BondIonic Bond = formed between ions
• Not as strong as Covalent
• Electrical charge; easily dissociated in water (electrolytes)
– Bananas, Gatorade) Ionic bonds
Hydrogen Bonds• Attraction between (+) and
(-) of an adjacent molecule• “Most” important in biology • Weakest of the three• Molecules may have polar
sites in their structure• Water dissolves many
things
Bonds and Function
• Shape of the molecule created by bonding forces determines function
• Ex. Proteins have specific shapes that allow only another molecule with the right shape to fit– Makes life chemistry
possible
• Shape of the molecule created by bonding forces determines function
• Ex. Proteins have specific shapes that allow only another molecule with the right shape to fit– Makes life chemistry
possible
WaterWater
• Life evolved in water (oceans)• 70% of earth covered with water• 70-90% of organisms are water• Philic = loving• Phobic = fearing• Hydro = water
Exists in all 3 states on the planet
Water: Hydrogen bonding
Water PropertiesWater Properties
• Cohesive = adheres to itself
• Adhesive = adheres to other substances, hydrophilic substances (glass, metals), meniscus
• Capillarity – water ‘creeps up thin tubes
• Transpiration in trees
• Cohesive = adheres to itself
• Adhesive = adheres to other substances, hydrophilic substances (glass, metals), meniscus
• Capillarity – water ‘creeps up thin tubes
• Transpiration in trees
WaterWater
• Surface tension -beading
• ex. waterstriders
Water Water
• High Specific Heat: - slow to change temperature
• Water will act as a heat ‘sink’, traps heat during summer and slowly releases heat during winter
• Moderates earth’s climate; coastal areas temperatures are milder
• Organisms are 70% water
• High Specific Heat: - slow to change temperature
• Water will act as a heat ‘sink’, traps heat during summer and slowly releases heat during winter
• Moderates earth’s climate; coastal areas temperatures are milder
• Organisms are 70% water
Water PropertiesWater PropertiesWater PropertiesWater Properties
• High Heat of Vaporization - amount of heat energy needed to cause a liquid to evaporate
• Evaporative cooling = cooling of a surface as water evaporates
• Molecules with the highest energy evaporate fastest – Molecules with less heat energy are left
behind (less heat = cooler) Radiators, dogs pant, Homeostasis
• High Heat of Vaporization - amount of heat energy needed to cause a liquid to evaporate
• Evaporative cooling = cooling of a surface as water evaporates
• Molecules with the highest energy evaporate fastest – Molecules with less heat energy are left
behind (less heat = cooler) Radiators, dogs pant, Homeostasis
Water PropertiesWater Properties
• Expands as it freezes: water contracts as it cools; at 4oC it expands and becomes less dense
• Bodies of water freeze at the top
• Colder water from bottom re-circulates nutrients to the surface (life)
• Expands as it freezes: water contracts as it cools; at 4oC it expands and becomes less dense
• Bodies of water freeze at the top
• Colder water from bottom re-circulates nutrients to the surface (life)
Water PropertiesWater Properties
• ‘Universal’ solvent: due to Polarity; (+) end pulls (-) end
• Solution – 2 or more substances mixed together (air)
• Solvent = dissolving agent (water); aqueous solution
• Solute = substance being dissolved
• ‘Universal’ solvent: due to Polarity; (+) end pulls (-) end
• Solution – 2 or more substances mixed together (air)
• Solvent = dissolving agent (water); aqueous solution
• Solute = substance being dissolved
SolutionsSolutions
• pH = measure of amount of H+ in solution
• Range of measure from 1-14
• 1-7 = ‘acid’• 7-14 = ‘base’, ‘alkaline’
• pH = measure of amount of H+ in solution
• Range of measure from 1-14
• 1-7 = ‘acid’• 7-14 = ‘base’, ‘alkaline’
pHpH
• A change in pH number (7 to 6) is exponential (tenfold)
• 7 to 5 = 100 fold increase in H+• 5.5 to 8.5 = 1000x increase (major change),
pollution
pHpH• Most biotic solutions = 6-8;
– Stomach = 1.5 - 2• Acid rain
– SO2, NO2 mix w/ water in atmosphere
– Lowers pH of lakes, soil
– Buffer = substance that prevents sudden, large changes in pH, weak acids or bases (bicarbonate)
Properties of WaterProperties of WaterProperties of WaterProperties of Water
• Cohesive; H bond• Adhesive; H bond• High specific heat; H bond• High heat of vaporization; H bond• Expands as it freezes• ‘Universal’ solvent; polarity