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Unformatted text preview: Biology 1201 Final Review StudyGuide Summary #1 1. Hierarchy of structural levels in biology 2. Properties of life 3. Science as a process 4. Scientific method Summary #2 1. Distinguish between an element and a compound. Matter consists of chemical elements in pure form and in combinations called compounds. Elements cannot be broken down to other substances. A compound contains two or more elements in a fixed ratio. 2. Identify the four elements that make up 96% of living matter. Life requires about 25 chemical elements; Carbon, oxygen, hydrogen, and nitrogen make up approximately 96% of living matter. 1 3. Describe the structure of an atom. Atomic structure determines the behavior of an element: An atom is the smallest unit of an element. An atom has a nucleus made up of positively charged protons and uncharged neutrons, as well as a surrounding cloud of negatively charged electrons. The number of electrons in an electrically neutral atom equals the number of protons. Most elements have two or more isotopes, different in neutron number and therefore mass. Some isotopes are unstable and give off particles and energy as radioactivity. 4. Understanding of atomic number, mass number, atomic weight, and valence and relationship to atomic structure. Electron configuration determines the chemical behavior of an atom. Electrons occupy specific energy levels, or shells, of the atom. Chemical behavior depends on the number of valence electrons, those in the outermost shell. An atom with an incomplete valence shell is reactive. Electrons move within orbitals, three-dimensional spaces with specific shapes located within successive shells. 5. Understanding of non-polar covalent, polar covalent and ionic bonds. Atoms combine by chemical bonding to form molecules: Chemical bonds form when atoms interact and complete their valence shells. A covalent bond is the sharing of a pair of valence electrons by two atoms. Molecules consist of two or more covalently bonded atoms. Electrons of a polar covalent bond are pulled closer to the more electronegative atom. A covalent bond is non-polar if both atoms are equally electronegative. Two atoms may differ so much in electronegativity that one or more electrons are actually transferred from one atom to the other. The result is a negatively charged ion (anion) and a positively charged ion (cation). The attraction between two ions of opposite charge is called an ionic bond. 6. Understanding of chemical equilibrium. Chemical reactions make and break chemical bonds. Chemical reactions change reactants into products while conserving matter. Most chemical reactions are reversible. Chemical equilibrium is reached when the forward and reverse reaction rates are equal....
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- Fall '07