Week 3 Chemistry 126 notes
Week 3 Chemistry 126 notes CHE 106 - M001
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CHE 106 - M001
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This 5 page Class Notes was uploaded by Andrea Scota on Sunday September 20, 2015. The Class Notes belongs to CHE 106 - M001 at Syracuse University taught by R. Doyle in Fall 2015. Since its upload, it has received 50 views. For similar materials see General Chemistry Lecture I in Chemistry at Syracuse University.
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Date Created: 09/20/15
Chem 106 Notes Week 3 TEXTBOOK NOTES CHAPTER 2 Atoms Molecules and Ions The Atomic Theory of Matter 21 Atoms are the basic building blocks of matter composed of subatomic particles Dalton s Atomic Theory 0 Law of conservation of mass postulate 3 the total mass of materials present after a chemical reaction is the same as the total mass present before it He used this to deduce the law of multiple proportions if two elements A and B combine to forms more than one compound the masses of B that combine with given mass of A are in the ratio of small whole s 0 Law of constant composition in a given compound the relative numbers and kinds of elements are constant The discovery of atomic structure 22 0 Thomson discovered positively and negatively charged electrodes using cathode rays the cathode rays were de ected towards entities because they were negatively charged The electron was discovered and given a charge 0 Millikan measured the charge and mass 910 X 103928g of the electron 0 Rutherford revealed 3 types of radiation alpha beta and gamma 0 Radioactivity spontaneous emission of radiation 0 Alpha and beta radiation consists of fast moving particles 0 Alpha particles have a charge and are attracted to 0 Beta particles are and attracted to 0 Thomson then predicts a quotplum pudding or watermelon with seeds structure for the atom That is inside the atom protons and electrons are freely oating 0 Rutherford gold foil experiment explains the nuclear model of an atom all of the atoms mass and positive charge reside in a small dense nucleus Rutherford suggests that most atoms are simply empty space in which electrons move around in 0 Rutherford discovers that protons charge reside in nucleus Chadwick discovers neutrons neutral charge which also reside in the nucleus The modern view of atomic structure 23 0 Electronic charge charge of electrons and protons 1602 X 103919 C o The charge of an electron is 1 the charge of a proton is 1 a neutron has no charge Angstrom atomic dimensions 1 angstrom 1 X 10mm 0 Atoms have diameters of approximately 15 angstrom 0 Diameter of atomic nucleus 10394 angstrom Atomic mass unit amu 1 amu 166054 X 10 3924g 0 Proton mass 10073 amu o Neutron mass 10087 amu 0 Electron mass 5486 X 10 394 amu Atomic number the number of protons in an atom the number of protons always equals the number of electrons while the number of neutrons can uctuate Mass number the number of protons neutrons in an atom Isotopes atoms with identical atomic numbers same atom but different mass numbers different numbers of neutrons Atomic weights 2 4 Use amu when dealing with eXtremely small masses 0 Presently de ned by assigning the mass of 12 amu to Carbon12 Most elements occur in nature as miXed isotopes Atomic weight atoms average atomic mass 0 Atomic weight Z isotope mass X fractional isotope abundance all isotopes of element Mass spectrometer most accurate means for determining atomic weight The Periodic Table 25 Most signi cant tool that chemists use for organizing and remembering chemical facts Set up in a strategic way Arrangement in order of increasing atomic number elements with similar properties in vertical columns Horizontal rows called periods Vertical columns called groups 0 Similar in chemical or physical properties Periodic Table of the Elements In a 3 II gt gt l1 6 ea r agar 39li39l LBLE 23 Names for Some of thlE groups in the Periodic TabIE Granny Name Ellernmts 1A Lir Na K lib C5 Fr Eli Alkaline ear i metals Be Mg Ca Sr Ba Ra lls Chalmgens Big 393 5e Te Po FA Hailingens F 21 En l it EA Noble gases or rare games He He Xe 0 Color code shows 0 All elements on leftin middle are metallic elementsmetals Share characteristic like luster high electricalheat conductivity 0 Nonmetallic elementsnonmetals separated from metals by stepped line from boron gt astatine At room temperature some are gaseous some solid and one is liquid 0 Metalloids have characterisitcs of both metals and nonmetals Molecules and molecular compounds 26 0 only noblegases are usually found in nature as isolated atoms 0 chemical formula tells how many atoms in molecules 02 subscript tells that 2 oxygen atoms present in each molecule diatomic molecule if molecule is made up of 2 atoms H O N and halogens 0 molecular compounds composed of more than one type of atom 0 most molecular substances we encounter contain only nonmetals 0 molecular formula chemical formulas that indicate the actual numbers if atoms in a molecule 0 empirical formulas chemical formulas that give you only the relative number of atoms of each type in a molecule used because certain common methods for analyzing substances lead to the empirical formula only 0 subscripts are always the smallest Whole possible number ratios 0 EX molecular formula for hydrogen peroxide is H202 vs HO 0 Structural formula shows how atoms are joined in the molecule 0 Ball and stick 0 Space lling models w relative sizes Ions and ionic compounds 27 0 Some atoms can readily gainlose electrons If electrons are removedadded to an atom the particle is called an ion 0 Cation positively charged by losing an electron superscript o Anion negatively charged by gaining an electron superscript o EX Na Cl39 Polyatomic ions consist of atoms joined as in a molecule but carrying a net negative or net positive charge 0 EX NH4 Noble gases are chemically nonreactive nearby elements can obtain stable arrangements by losinggaining electrons Ionic compound a compound made up of cations and anions o In general cations are metal ions and anions are nonmetal ions 0 Ionic compounds are generally combinations of metals and nonmetals 0 Contrast molecular compounds are generally composed of nonmetals ONLY H20 0 Ionic compounds are electrically neutral so they usually contain metallicnonmetallic elements Polyatomic ions atoms that are joined together as in a molecule but carry a net charge 0 Chemical formulas used for ionic compounds are empirical can be written readily if charges of ions are known 0 One Na to one C139 in NaCl one Ba2 to two C139 in BaClz Charges of all anionscations in compounds are equal Naming inorganic compounds 28 0 Chemical nomenclature the system used in naming substances 0 Rules are based on division of substances into categories major division organic vs inorganic 0 Organic contain carbon and hydrogen only inorganic contain all other elements ionic compounds molecular compounds acids 0 Cations named rst then anions 1 Cations are formed from metal atoms have the same name as the metal a If a metal can form cations with different charges the positive charge is indicated by a roman numeral in parentheses following the name of the metal b Cations formed from nonmetal atoms have names that end in 1um 2 Anions the names of monatomic anions are formed by replacing the ending of the name with ide a Polyatomic anions containing oxygen and another element oxyanions have names ending in ate or ite 3 Ionic compounds a Names of ionic compounds consist of cation name followed by anion name 4 Acids a Acids with ide ending change to ic ending and then adding hydro to anion name followed with the word acid hydrochloric acid b Acids anions ending in ateite change to iteic ite ous then add word acid to the end perchloric acid 5 Binary molecular compounds a Name of element farther to left in periodic table is usually written rst b If both elements are in the same group then the one closer to the bottom of the table is named rst c Name of the second element is given ide ending d Greek prefixes Some simple organic compounds 29 Organic chemistry is the study of compounds of carbon compounds that contain carbon and hydrogen usually contain O and N Hydrocarbons are simplest class of organic molecules they contain ONLY hydrogen and carbon Alkanes hydrocarbons in which each carbon atom is attached to 4 other atoms names end in ane methane ethane Other organic compounds are formed when hydrogen atom of a hydrocarbon is replaced with a functional group Alcohol compound in which a hydrogen atom of hydrocarbon is replaced by an OH names end in ol menthol ethanol Isomers compounds with same molecular form but different bonding arrangements
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