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