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

Water 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 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

Water Surface tension -beading ex. waterstriders

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 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 Properties Expands as it freezes: water contracts as it cools; at 4 o C 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 4 o C 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 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

Solutions pH = measure of amount of H + in solution Range of measure from = ‘acid’ 7-14 = ‘base’, ‘alkaline’ pH = measure of amount of H + in solution Range of measure from = ‘acid’ 7-14 = ‘base’, ‘alkaline’

pH 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

pH Most biotic solutions = 6-8; –Stomach = Acid rain –SO 2, NO 2 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 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