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Atoms and molecules
biol 1210
| Question | Answer |
|---|---|
| matter | anything that takes up space and has mass. it consists of chemical elements in pure form or in compounds |
| 4 major elements that make up most living matter | C, H, N, O |
| 3 physical & 3 chemical properties of matter | physical: mass, volume, boiling/melting point. Chemical: reactivity, flammability, toxicity |
| energy is matter. T/F | F |
| chemical element | substances that contain only one type of atom. Cannot be broken down into other substances by chemical reactions. Consists of atoms |
| atom | the smallest unit of matter that retains the properties of an element. Consists of subatomic particles. Makes up elements. |
| name 3 main subatomic particles & each charge & location | proton - positive, in nucleus; neutron - neutral, in nucleus; electron - negative, outside nucleus in shells/orbitals |
| atomic number | the # of protons in an element's nucleus - that # is unique to a single element (if it changes, the element changes) |
| atomic mass | the sum of the protons + neutrons in the nucleus |
| # of electrons | equal to the # of protons in uncharged atoms |
| compound | substance that contains 2+ elements in a fixed ratio. More common than elements in living organisms |
| general structure of an atom | a nucleus w protons & neutrons surrounded by energy shells of electrons - the farther energy shells are from the nucleus, the higher the energy level of the electrons |
| valence electrons and valence shells | valence shell: the outermost energy shell of an atom. Valence electrons: electrons in the valence shell that determine the chemical behaviour of an atom |
| relative reactivity of atoms with complete and incomplete valence shells | complete valence shells - chemically inert, do not react. Incomplete valence shell - chemically reactive |
| emergent properties of a compound | determined by the arrangement of atoms. Different from from the properties of the elements that make it up |
| chemical bond | attractions that hold atoms together and are the result of interactions between atoms with incomplete valence shells sharing or transferring valence electrons |
| types of chemical bonds | covalent (polar & non-polar), ionic & hydrogen |
| valence of an atom | # of unpaired electrons in the valence shell |
| covalent bond | result from the sharing of a pair of valence electrons by two atoms, which count as part as each atom's valence shell |
| molecule | 2+ atoms covalently bonded together |
| nonpolar covalent bond | atoms have very similar or identical electronegativities and share the electrons equally |
| polar covalent bond | one atom is more electronegative and the atoms do not share the electrons equally. This leads to slightly positively and slightly negatively charged ends of the molecule |
| ion and cations v. anions | ion: a charged atom or molecule. Cation: positively charged ion, anion: negatively charged ion |
| ionic bonds | form when atoms transfer electrons and are held together by the attraction of a cation to an anion. |
| hydrogen bonds | form between polar molecules due to the unequal distribution of charges (partial positive end of one polar molecule is attracted to partial negative end of other polar molecule). Associated with H which has partial positive charge. Very weak bonds |
| in biological systems, which is less stable: ionic or covalent bonds, and why? | ionic bonds are less stable because water, the biological media of life, is polar and pulls the ionic bonds apart. |
| salts | compounds formed by ionic bonds. Often found naturally as crystals and dissolve easily in water |
| chemical reactions | the rearrangement of matter but matter is not created or destroyed. Materials: reactants, results of a reaction: products. |
| reaction rate | how many products are being produced; evaluated by the # of reactants consumed and/or # of products produced |
| describe the water molecule | polar molecule with 1 slightly negative and 2 slightly positively poles; polarity leads to hydrogen bonding due its structure (angle, size & electronegativity of atoms). Made of polar covalent bonds between 2 H and 1 O. |
| emergent properties of water | all related to the hydrogen bonding of water molecules: Cohesive behaviour, ability to moderate temp, expansion upon freezing, versatility as a solvent, chemical reactivity |
| cohesion | tendency of molecules of the same kind to stick together. Hydrogen bonds hold water molecules together, making it especially cohesive |
| adhesion | when molecules of different kinds stick together |
| how do the cohesive and adhesive properties of water allow water to move up in a tree? | Water's cohesion allows it to stick together and stay together and the adhesion of the water molecules to the walls of the xylem allows it to climb upward by capillary action |
| how does hydrogen bonding between water molecules make it a good temperature stabilizer? | Hydrogen bonds are strong and resistant to both increases and decreases in temp. They take lots of energy to break, and then energy is released when the bonds reform. This allows water to absorb a lot of heat and cool off slower |
| how do hydrogen bonds between water molecules help make ice less dense than water? | Hydrogen bonds become more ordered as they freeze and form crystals that are less dense than water in its liquid state by creating more space in between the molecules |
| solution, solvent, solute | solution: homogeneous mixture of substances, solvent: dissolving agent of a solution, solute: a substance dissolved in a solvent |
| how does the polarity of water make it such a versatile solvent? | The polarity of water allows it to dissolve a wide variety of ionic compounds and polar molecules easily because it has partial positively charged and partial negatively charged ends |
| hydrophobic v. hydrophilic substances | hydrophobic: relatively nonpolar, do not have affinity to water, interact with each other thru hydrophobic interactions. Hydrophilic: some degree of polarity and have affinity for water |
| chemical reactivity of water | due its polarity, water takes part as a reactant in many biochemical reactions (ex. hydrolysis) |
| inorganic compounds | small & simple, substance that doesn't contain carbon-hydrogen bonds, often has ionic bonds, ex. salts, acids, bases, H2O, CO2 |
| organic compounds | large & complex, compounds that always contain C-H bonds, carbon main element, contains covalent bonds, ex. carbs, lipids, proteins, nucleic acids |
| describe molecular diversity and carbon | almost all molecules of life are made of C - C can make 4 covalent bonds and chains of varied length & shape that form C skeletons of organic molecules. Diversity from variation in C skeletons |
| hydrocarbons | organic molecules consisting ONLY of C & H, nonpolar, hydrophobic. Most organic compounds contain hydrocarbons & they can undergo reactions that release large amoutns of energy (often used to store energy) |
| functional group | specific configuration of atoms commonly attached to the C skeletons of organic molecules & involved in chemical reactions. # & arrangement of FG give each molecule unique properties. All FG are polar & therefore soluble in water |
| methyl group | also impact molecular shape & function but they are nonpolar and unreactive |
| hydroxyl group | -OH attached at the end of a chain. Found in alcohols |
| carbonyl group | =O in the middle or at the end of a chain. Found in carbs |
| carboxyl group | often OH-C=O at end of chain where C is the end carbon (-COOH), may be carboxylic acid or ionized form. Found in ethanol, proteins |
| amino group | -NH2 with N attached at end of C chain. May be Amine or ionized form. Found in proteins |
| phosphate group | -OPO_3_2- consisting of P single bonded to 3 O and double bonded to 1 O, negatively charged. Found in nucleic acids, ATP |
| methyl group | -CH3, makes methylated compounds, only nonpolar functional group. |
| macromolecules | large molecules composed of thousands of covalently bonded atoms |
| 4 classes of macromolecules (which involve polymers?) | carbs, proteins, nucleic acids, lipids. All have polymers except lipids |
| polymer | large molecule consisting of a chain of many identical or similar molecular units strung together |
| monomer | units that serve as building blocks for polymers |
| polymerization | connecting monomers into a chain polymer |
| how are polymers diverse and how does this affect organisms? | trillions of different polymers exist made by only ~40-50 monomers. The key to variation is the sequence in which monomers are strung together |
| how are polymers assembled? | cells link monomers together to form polymers by dehydration synthesis: one monomer gives up a H atom and another gives up a OH group = water is released and a new covalent bond forms between the monomers |
| how are polymers disassembled? | polymers are broken apart by hydrolysis (the reverse of dehydration synthesis) - adding a water molecule |
Created by:
AntBanana
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