CHAPTER 2

CHAPTER 2 - CHAPTER 2 – ATOMS AND MOLECULES THE CHEMICAL...

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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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CHAPTER 2 - CHAPTER 2 – ATOMS AND MOLECULES THE CHEMICAL...

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