CHM 113, Week 3 Notes
CHM 113, Week 3 Notes CHM 113
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This 4 page Class Notes was uploaded by Leslie Jaimes on Saturday February 6, 2016. The Class Notes belongs to CHM 113 at Arizona State University taught by Briggs in Fall 2015. Since its upload, it has received 21 views. For similar materials see General Chemistry I in Chemistry at Arizona State University.
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Date Created: 02/06/16
Chapter 2 I. Daltons Atomic Theory (1803 – 1807) a. Elements are composed of very small particles (atoms) b. All atoms of the same element are identical c. Atoms of one element can’t be changed into atoms of different elements d. Compounds are formed when atoms of more than one element combine e. Compounds always have the same relative number and kinds of atoms (law of constant composition) i. EX: H2O f. Atoms cannot be created nor destroyed in a chemical reaction (law of conservation of matter) II. Atomic Structure a. J.J. Thomson (1897): discovered a stream of electrons (cathoderay) by applying a potential through two electrodes in an evacuated glass tube b. Robert Millikan (1909): used Thomson’s data to calculate the charge and mass of an electron in his O−19Drop Exp8riment −28 i. Electron Mass = 1.60x10 c/1.76x10 cg=9.10x10 ii. Oil Drop Experiment/ Thomas’s Data c. Ernest Rutherford (1910): Alpha Particle Scattering Experiment – proved the existence of a dense, positive nucleus (and disproved Thomson’s “Plum Pudding” Model) d. Ernest Rutherford (1919): discovered the proton e. James Chadwick (1932) discovered the neutron f. Elementary (Subatomic Particles) PARTICL EYMBOL ACTUAL RELATIV MASS E CHARG E (AMU) E CHARGE Electron e^- -1.602 x -1 5.486 10^19c x 10^- 4 Proton p^+ +1.602 +1 1.0073 x 10^- 19c Neutron n 1.0087 1amu = 1.66054 x 10^-24g I. Structure of The Atom a. Dense nucleus in the center b. Nucleus contains all p+ and n c. Low mass e^- and mostly empty space II. Atomic and Mass Number a. Mass number: number of p+ and number of n b. Element symbol c. Atomic number: number of p+ d. We must write the mass number because of isotopes e. Isotopes: different types of the same element with different masses due to a different number of n. they can be: 1. Stable 2. Radioactive 3. Occur naturally 4. Man made f. Isotopes can be written with either a dash or a super script for the mass number i. EX: carbon – 12 or 12C (6p+, 6n, 6e^-) ii. EX: carbon – 13 or 13C (6p+, 7n, 6e^-) g. The atomic mass of the periodic table is the weighted sum of the masses of all naturally occurring isotopes of an element i. Atomic mass of Cl = 34. III. The Periodic Table a. 118 known elements i. #1 – 98 occur naturally on earth ii. Most are solid and metallic iii. Element #84 and above are radioactive, and many are man- made b. Layout of the Periodic Table (PT) i. Elements are listed by: Atomic # (z), symbol, atomic weight ii. …and arranged in columns and rows iii. Columns (groups): up/down sections on PT iv. Each is labeled with a group # (1-8) and a letter (A for main group elements, B for transition elements) 1. EX a. Na = group 1A b. O = group 6A c. He = group 8A d. Ti = group 4B e. Cu = group 1B f. Fe, Co, Ni, group 8B v. Some periodic tables use roman numerals and some number groups from #1 – 18 vi. A and B are designations are of len omitted vii. Rows (periods): left/right sections, numbered 1-7 viii. Three main categories: 1. Representative (main group) elements: groups 1A, 2A, 3A – 8A most abundant, how the strangest trends every 8 elements ix. Transition metals (d-block elements): group 3B – 2A (middle of periodic table) x. Lanthanides and Actinides (inner transition metals, f – block elements, rare earth metals): elements at bottom of the periodic table (follow La and Ac) c. Types of Elements and locations i. Alkali metals: group 1A (except H) ii. Alkali Earth Metals: group 2A iii. Noble gases: group 8A iv. Metalloids: B, Si, Ge, As, Sb, Te v. Metals: elements left of metalloids (except H) vi. Nonmetals: elements right of metalloids (and H) vii. Chalcogens: group 6A viii. Halogens: group 7A d. Typical properties i. Metals 1. High luster (shinny) 2. Good conductors 3. Ductile (stretch into wires) 4. Malleable (hammer into sheets) 5. High density and melting point – all solids at 25*C (except Hg) ii. Nonmetals 1. Most are gases – solids are hard and brittle, no luster (dull) 2. Do not conduct electricity, poor conductors ( except C,P, Se) 3. Low density and low melting point (except C) iii. Metalloids 1. Solids at room temperature 2. Properties of metals and nonmetals a. Can be shiny or dull b. Hard and brittle c. Poor thermal conductivity d. Moderate electrical conductivity iv. Noble gases 1. Invisible gases 2. Very nonreactive IV. Naming chemical compounds a. Two things to learn how to name: i. Free (uncombined) element 1. Memorize elements/ symbols from Ch 1 handout 2. Recognize the same exist naturally as diatomic molecules a. Nz, Oz, Hz, Halogens: Fz, Clz, Brz, Iz ii. Compounds of two or more different elements (nomenclature rules) b. Oxidation States (PG. 140 – 141) c. Valence electrons (VE) = e^- farthest way from the center of an atom (and closest to the VE’s of a neighboring atom) shared VE’s result in a covalent bond d. Oxidation Number (ON) = number that indicates the change in the number of VE’s between an element by itself and when it’s part of a compound i. We use ON’s to predict ion charges, write chemical formulas, and name ionic compounds e. Five Rules for assigning ON’s (examples) i. C, each O in O2, each H in He, Fe, Ar has ON = 0 ii. Ion = charged species that has more of less e^- than a neutral element 1. Anron: (-) ion results from adding one or more e^- to a neutralaten 2. EX: Cl^-, N^3-, O^2- 3. EX: -1, -3, -2 iii. Cation: (+) ion. Results from removing one or more e^- from a neutral atom 1. EX: Na^+, Mg^2+, Cr^6+ 2. EX: +1, +2, +6 iv. The ON of Li in Lih is +1 1. “ “ “ “ Ca in CaCl2 is +2 2. The ON of Zn in ZnS is +2 3. The ON of each Al in Al203 is +2 v. MgF2 - +2 , -1(2) = -2 1. NaH - +1 , -1 2. K2O2 – +1(2) = +2, -1(2)= -2 3. H2O – +1(2)= -2, -2 4. CO2 – +4, -2(2) = -4 5. NH3 – -3, +1(3) = +3 6. CCl4 – +4, -1(4)= -4 7. SO4^2- - +6, -2(4)= -8 8. Cr2O3 – +3(2) = +6, -2(3) = -6 9. Cr2O7^2- - +6(2) = +12, -2(7) = -14 10.HNO3 – +1, +5, -2(3) = -6
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