BSC 114, Chapter 2 Notes
BSC 114, Chapter 2 Notes BSC 114
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This 4 page Class Notes was uploaded by Rebecca Sharp on Monday January 18, 2016. The Class Notes belongs to BSC 114 at University of Alabama - Tuscaloosa taught by Stevan Marcus in Winter 2016. Since its upload, it has received 86 views. For similar materials see Principles Of Biology I in Biological Sciences at University of Alabama - Tuscaloosa.
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If Rebecca isn't already a tutor, they should be. Haven't had any of this stuff explained to me as clearly as this was. I appreciate the help!
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Date Created: 01/18/16
Chapter 2 BSC 114 Vocabulary: Bio Basics Organisms are any contiguous living systems made of matter -> matter is everything that has mass and takes of space, is made of elements -> elements cannot be broken down any farther and make up all biological material Compounds are 2+ elements. There is a fixed ratio of the amount of each element involved, and the compound does not necessarily retain the properties of its elements Atomic number is the number of protons in an atom (written to the lower left of an atom) Atomic mass is the number of protons and neutrons in the atom (written to the upper left of the atom) atomic mass is measured in atomic mass units, or daltons Isotopes are different forms of the same element, differing only in the number of neutrons. They are not always stable. Half Life is the amount of time it takes for half of the sample element to decay Energy is the ability to do work to cause change Electron Shells are the planes in which the electrons exist. Electron location can never be pinned down 100% as explained by the Heisenberg Uncertainty Principle. Valence Electrons refer to the number of electrons in the outermost Electron Shell Valence Electron Shell refers to the outermost electron shell Covalent Bonds occur when 2 or more atoms get together too share electrons to complete the number of electrons in their valence shells Ionic Bonds occur when an atom rips away the electrons it needs from another atom, resulting in a negative atom and a positive atom which are attracted to each other by virtue of their polarity. The pair ionically bonded does not have to have stolen electrons from each other, but they have to be polar. Bonding Capacity is the number of covalent bonds an atom is capable of making based on its number of valence electrons (ie oxygen, with 2 valence electrons, has a bonding capacity of 2) Also called the atom’s valence. It equals the number of electrons needed to complete the valence shell. Electronegativity is the attraction of a given atom for electrons in a covalent bond. The higher the electronegativity, the harder that atom pulls on the shared electrons Nonpolar Covalent bond means that there is no net charge on either atom in a given covalent bond, occurs when the atoms have equal electronegativity Polar Covalent bonds are when there is an electronegativity imbalance, which results in a positive charge on the atom with lower electronegativity and a negative charge on the atom with the higher electronegativity Molecules are the smallest piece of a chemical reaction, a molecule is a group of atoms bonded together Ionic Compounds, AKA “salts” are not molecules. Salts are a set ratio of elements, not a set number of them like covalent compounds. Cation is a positively charged ion (Ions are just charged atoms) Anion is a negatively charged ion (Ions are just charged atoms) Chemical Reactions: Reactants are the things you put in to a chemical reaction to make things happen Chemical Reactions: Products are the things you get out of a chemical reaction after things happen Explanations, Elaborations, and Fun Facts The Important Elements Only 20-25% of the elements are essential to life; 17 for plants and 25 for humans Oxygen, Carbon, Hydrogen, and Nitrogen make up 96% of living matter Atom Stats Proton Mass is expressed as 1.7E-24 grams, which is one millionth of one billionth of one billionth, as 1 amu, which is an atomic mass unit, or as 1 dalton. Neutron Mass is expressed as 1.7E-24 grams, which is one millionth of one billionth of one billionth, as 1 amu, which is an atomic mass unit, or as 1 dalton. Yeah, they’re equal Electrons basically have negligible mass; 1/2,000 amu Radioactivity Radioactive Isotopes of elements have spontaneously decaying nucleases. Cells can still use radioactive isotopes just like they would non- radioactive isotopes This has led to RIs being used as tracers to help visualize cell metabolism Half lives range in duration from seconds to billions of years. Electron Energy and Valence Electrons have the greatest potential energy farthest from the nucleus Electron potential energy moves in stair steps, not as a gradual curve This is because electrons can’t spend much time between electron shells, they jump from level to level too quickly The distribution of electrons within the electron shells determines its chemical behavior Shell 1 only has a spherical s orbit, and so only holds 2 electrons Shell 2 has an s orbit as well as three dumbbell-like p orbits, and so holds 8 electrons The chemical behavior of atoms is determined by the number of valence electrons it has Only electrons are directly involved in chemical reactions because electrons are mostly empty space Atomic Bonds The strongest bonds are covalent bonds and (dry) ionic bonds A pair of atoms bonded by a covalent bond make a molecule A pair of atoms bonded by an ionic bond do not make a molecule Bonding Capacity for covalent bonds gets complicated in the 3 row of the periodic table and varies from element to element. For example Phosphorus has 3 unbounded electrons, but can form 3 single bonds as well as a double bond, giving it a bonding capacity of 5. Weak bonds play a huge role in atomic chemistry as well as just (dry) ionic and covalent bonds because weak bonds can be broken Hydrogen Bonds occur when a hydrogen atom is covalently bonded to an electronegative atom. The hydrogen becomes positively charged which allows it to be attract and connect to other negative atoms. Hydrogen bonds hold DNA together. When an ionic compound gets wet, it dissolves but is still weakly bonded within the solution allowing multiple atomic interactions Van der Waals Interactions are a result of constant electron movement, which allows even nonpolar molecules to have polarity, in that they have slightly positive and slightly negative regions. This can make things stick together, so long as they’re close together. The ability of geckos to run straight up walls has been attributed to Van der Waals Interactions. Molecular Shape Molecular shape determines how an atoms recognize and interact with one another If they have complimentary shapes, they can form temporary weak bonds This is how heroin works, the molecular shapes bond to endorphin receptors in the brain which means the real endorphins can’t link up the way they should. One Last Word on Chemical Reactions Matter is always conserved in a chemical reactions. Even though the thing you get out of it, the product, looks different from the thing you put in, the reactants, it’s the same amount of matter that has been scrambled up. All chemical reactions are reversible, they can all go both ways Chemical Equilibrium happens when the reaction is going forwards as fast as it is going backwards. It’s a dynamic equilibrium, which means that even though it has reached a form of stasis it’s still moving but it’s moving equally in both directions.
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