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Unformatted text preview: CHAPTER 2 ATOMS AND MOLECULES: THE CHEMICAL BASIS OF LIFE Molecular biology o The chemistry and physics of the molecules that constitute living things Inorganic compounds o Small, simple substances Organic compounds o Carbon containing compounds that are generally large and complex ELEMENTS AND ATOMS Elements o Substances that cannot be broken down into simpler substances by ordinary chemical reactions Chemical symbol o Usually the first letter or first two letters of the English or Latin name of the element Atom o The smallest portion of an element that retains its chemical properties Matter o Anything that has mass and takes up space Electron o A particle that carries a unit of negative electric charge Proton o A particle that carries a unit of positive charge Neutron o And uncharged particle Atomic nucleus o Made up of protons and neutrons clustered together An atom is uniquely identified by its number of protons Atomic number o Fixed number of protons in the atomic nucleus Periodic table o Chart of the elements arranged in order by atomic number Electron configurations o Bohr models o Show the electrons arranged in a series of concentric circles around the nucleus Protons plus neutrons determine atomic mass Atomic mass unit (amu) o Unit of mass of a subatomic particle Dalton o Unit used to express amu Atomic mass o Number that indicates approximately how much matter it contains compared with another atom o Protons + neutrons Isotopes of an element differ in number of neutrons Isotopes o A mixture of atoms different numbers of neutrons Radioisotopes o Unstable isotopes that tend to break down, or decay, to more stable isotopes Autoradiography o A method used to detect radioactive decay in which radiation causes the appearance of dark silver grains in photographic film Electrons move in orbitals corresponding to energy levels Orbitals o Characteristic regions of 3-D space Principal energy level o Electrons in orbitals with similar energy levels Electron shell o Made up of electrons at principal energy levels Valence electrons o Most energetic electrons o Occupy the valence shell Valence shell...
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This note was uploaded on 04/04/2008 for the course BIO 101 taught by Professor Martin during the Fall '08 term at Rutgers.
- Fall '08
- molecular biology