BIOL 111 1st Edition Lecture 1 Outline of Current Lecture II. Scientific InquiryIII. WaterIV. Carbon CompoundsCurrent Lecture- Molecule-two or more atoms held together by a chemical bond- Compound-two or more different elements held together by chemical bonds, has different propertied from elements alone - So then what is an atom?o The smallest unit that has both the physical and chemical properties of an elemento Subatomic particlesCharge Mass LocationProton Positive 1 amu/Dalton NucleusNeutron Neutral 1 amu/Dalton Nucleus Electron Negative 0 Cloud o The number of protons in the nucleus will identify the element o The number of protons will be the atomic number- Physical properties of atomso Atomic number-the number of protonso Mass number/atomic mass-the number of protons plus the number of neutrons These two are added up because they are the things that will give the atom masso Isotopes-same number of protons but will have different numbers of neutrons, therefore giving it different atomic masseso Most of the chemical properties will come from electrons- Chemical properties of atomso Electron shells-where the electrons of the elements areo Valence shell-the outermost shell of all of the electron shells Concerned with this shell because this shell is where the bonding between elements occur- Chemical bondso Covalent-the electrons in the valance shell are being shared Non-polar covalent-equal sharing of electrons between the two elements Polar covalent-unequal sharing of electrons between the two element (the electrons are more attracted to one element than the other) Polar covalent bonds and electronegativity- Electronegativity-property of an atom to have a greater attraction to electrons in a bondo Ionic-electrons are transferred from one atom to another due to electronegativity; creates ions The atoms created are now ions because they are charged Salts dissolve in water and there are weak attractions between + and – poleso Hydrogen bond/Van der Waals forces/interactions Weak intermolecular forces that involve attractions between + and – poles (ex. Hydrogen bonding) Hydrogen bond: weak chemical bond between a H atom and an electronegative atom (such as O, N, S, or P)- Chemical reactionso Making and/or breaking chemical bonds leading to production of NEW compounds C6H12O6 + 6O2 6H2O + 6CO2 Right hand side-reactants, left hand side-products, the process above is cellular respiration- Why is water important to life/biology?o Cells need to have some source of water around in their lifecycle to liveo Environments need water to keep its organisms healthyo Biological regulations need water to maintain the systemo Ice is formed by water- How does the chemical structure of water explain:o Cohesion-something that bonds to itself Due to hydrogen bonding, water can bond to itself very easilyo Adhesion-water adheres to things very easily because it can form hydrogen bonds with other substanceso High specific heat-amount of heat that needs to be applied to 1 gram of a substance to raise its temperature 1 degrees Celsius o Floating ice-as water cools down, the hydrogen bonds that break between water molecules and the hydrogen bonds become more stable Since hydrogen bonds are more stable, ice is less dense than water and ice is ableto float Hydrogen bonds, while water is liquid, are constantly breaking and remaking o Hydrophilic interactions- Life is in aqueous solutiono Most biological chemistry involves solutes dissolved in water Solutes are the things being dissolved in water, solvent is the water (solvents dissolve solutes)o Need to calculate concentrationso Molecular mass=mass of all atoms in a molecule Ex. NaCl= 23 + 35 = 58 Daltonso Terms for solute concentrations in aqueous solution: Molarity (M)=moles of solute/liter Mole=6.02 X 1023 objects or Daltons/gram [similar concept=dozen=12 objects Molar mass=grams/moleo Notes and pH and buffers Water can dissociate into IONS: - 2H2O H3O+ + OH-—or—H2O H+ + OH- - Acid—any substance that increase H+ in a solutiono Donate H+ in an aqueous solution- Base—any substance that increase OH- in a solutiono Donate OH- or accept H+ in an aqueous solutiono Behavior of acids and bases in aqueous solution is CONSTANT @ 25 degrees C can be expressed as: [H+] [OH-] = 10=14 which is a very small # Can be expressed logarithmically: pH (potential of hydrogen) =-log [H+]- Bufferingo Since most living cells exist between pH 6.5-8.0o Buffering molecules in/around cells miniminze changes in [H+] and [OH-] by accepting- How does the electron configuration of carbon make it a useful building block?o 4 covalent bonds 4 valence electrons which gives carbon the ability to share one of the valence electrons with another atom and will form a covalent bond o Diverse arrangements possible Length Branching Double bonds Rings o Forms large complex molecules Major component in the four large biological
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