biology, week 2
biology, week 2 BIOL 2107
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This 2 page Class Notes was uploaded by Alexandra Irvin on Tuesday August 23, 2016. The Class Notes belongs to BIOL 2107 at Georgia Southern University taught by Lace Svec in Summer 2016. Since its upload, it has received 4 views. For similar materials see principles of biology I in Biology at Georgia Southern University.
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Date Created: 08/23/16
PRINCIPLES OF BIOLOGY I WEEK 2 Vocabulary: 1. Electronegativity: the ability of an atom to pull electrons to it’s nucleus. 2. Covalent bond: when two atoms share one or more valence electrons; often two nonmetals. 3. Polar covalent bond: a covalent bond (above) between atoms that differ in electronegativity (above); the shared electrons have higher attraction to the atom with the higher electronegativity, causing partial charges to occur. 4. Nonpolar covalent bond: a covalent bond where electrons are shared equally between two atoms of similar electronegativity; allows the atoms to acquire a neutral charge. 5. Ionic bond: the attraction between two oppositely charged atoms; often a metal and nonmetal. 6. Hydrogen bond: weak bond; + hydrogen atom of a polar bond is attracted to atom of a polar covalent bond. 7. Ion: when an atom(s) gains or loses on or more electrons, acquiring a charge. 8. Hydrophilic: liking water; being attracted to water. 9. Hydrophobic: fearing water; being repelled from water. 10. Functional group: a specific configuration of atoms commonly attached the the carbon skeletons of organic molecules that are involved in chemical reactions. Notes: Almost all life consists of: o Carbohydrates o Nucleic acid o Lipids o Protein Hydrogen atom: Electrons float around a ++ Nucleu _ s (p+, predetermined shape n) Oppositely charged objects attract; like _ Electron cloud (-) Electrons are maintained in energy shells (the distance they can travel from the nucleus due to the attraction to the protons). o Ex: ND 2 shell: 4 + 1 shell: 1 orbital; low energy level 3 shell: 4 orbitals; higher energy level within these shells are orbitals, where the electron will spend most of it’s time. Each individual orbital holds two electrons. The outermost shell is important for interactions Potential energy increases as you go out/up in energy shells. When two hydrogens bump into each other: Hydrogen has one valence electron = very unstable. o Both atoms have a chance to share and fill valence shells. o Electrons go back and forth between the two atoms (tug of war). o Creates a nonpolar covalent bond allow atoms to remain uncharged, sharing electrons equally (because of tug of war, electrons travel back and forth between the two). o High potential energy because electrons are being pulled either way at any given time. o The two atoms are being held together by: 1) filling orbitals (all atoms want their valence shell to be full). 2) attraction between electrons and protons in the two atoms. When hydrogen and oxygen bump into each other: o Oxygen has a high electronegativity, which means it is winning the “tug of war” of electrons. o Polar covalent bond sharing electrons unequally, creates partial charges (+ hydrogen; oxygen). o Hydrogen has one less electron while oxygen acquires an extra electron, because hydrogen’s electronegativity is less than that of oxygen. o Lower potential energy, because there is little competition over the single electron, oxygen’s electronegativity is simply to high/the attraction is too strong.