2 Topics of Discussion Summarize the Development of Atomic Theory Examine Atomic Structure
3 Laws Law of Conservation of Mass Law of Definite Proportions 3/25/2017LawsLaw of Conservation of MassLaw of Definite ProportionsLaw of Multiple Proportions
4 Laws Law of Conservation of Mass Mass is neither Destroyed 3/25/2017LawsLaw of Conservation of MassMass is neither Destroyednor Created during ordinaryChemical or Physical Reactions
5 Laws Law of Definite Proportions A Chemical compound contains the same elementsin exactly the same proportions, by Mass,regardless of size of sample or source of compound
6 Laws Law of Multiple Proportions If 2 or more different compounds are composed of the Same 2 Elements,then the ratio of the 2nd. element combined with the a certain mass of the 1st. element is alwaysa ratio of small whole numbers
7 Development of Atomic Theory DemocritusBelieved that matter was made up of atomsAtoms were invisible particlesAtoms were indestructible particlesLost out to Aristotle who stated that matter was continuous
8 Development of Atomic Theory Dalton (1808)Explains the Laws of conservation of mass, definite proportion and multiple proportionElements are composed of extremely small particles called atomsAtoms of the same element are identical in size mass and properties. Atoms of different elements differ in size. Mass and properties
9 Development of Atomic Theory Dalton (1808) cont.Atoms cannot be subdivided, created, or destroyed.Atoms of different elements combine in simple whole-number ratos to form chemical compoundsIn chemical reactions , atoms are combined, separated or rearranged
10 Development of Atomic Theory J.J. Thomson (1897)Discovers the electron(mass and a high charge)Proposes the “Plum-Pudding“ modelAtom is neutralElectrons embedded in a sphere of positive charge
11 Development of Atomic Theory Rutherford (1911)Gold foil experimentDiscovers that the atom has a nucleusExtremely smallExtremely densePositive chargeElectrons move around the nucleus
13 Development of Atomic Theory Bohr (1913)Electrons circle nucleus in specific circular paths at fixed distances from the nucleusEach electron orbit has a Specific Energy or energy levelA Quantum of energy is required to move from one orbit to the nextWorks for Hydrogen only!
14 Development of Atomic Theory 3/25/2017Development of Atomic TheoryMillikan discovers electron charge and Mass of an electron (1909)Chadwick discovers Neutron (1932)De Broglie proposes particle wave behavior of Electron (1923)Schrödinger writes an equation to determine probability of electron location
15 Development of Atomic Theory Electron Cloud Model (present)Based on Schrödinger's wave equationVisual model of the probable locations of the electron in an atom
17 Atomic Structure Properties of sub-atomic particles 3/25/2017Atomic StructureProperties of sub-atomic particles(proton, neutron, & electron)ChargeLocation in AtomSymbolsA(mass number) & Z (atomic number)Proton Atomic Number = ZPositive charge p+ , 11Hnucleusaccounts for atoms MassNeutron no charge n0, 10naccounts for atoms massElectron negative charge e-, 0-1eCloud around the nucleusmass but very small compared to proton or neutronaccounts for atom sizeNuclear forces hold nucleus togetherMass Number A= #protons +#neutronsAtomic Number = Z = # protonsAll atoms are electrically neutral = #electrons = #protons
18 Atomic Structure PROTON Location Center of atom; nucleus area Charge SymbolCenter of atom; nucleus areaPositivepATOMIC NUMBER (Z) = number of protons in the atom
19 Atomic Structure Neutron To find the number of neutrons in an atom: LocationChargeSymbolCenter of atom; nucleus areaNo charge (0)nTo find the number of neutrons in an atom:Mass number of the element – number of protons (atomic number) = A (number of neutrons
20 In a neutral atom, # of electrons = # of protons Atomic StructureElectronLocationChargeSymbolIn shells around the nucleus of the atom.NegativeeIn a neutral atom, # of electrons = # of protons
24 Atomic Structure Isotopes are: Naturally occur or man made 3/25/2017Atomic StructureIsotopes are:Atoms of the same elementThat have different massesNaturally occur or man madeNuclide general erm for any isotope of any element
25 Atomic Structure Practice: 1. Element D has 6 protons and 7 neutrons. 3/25/2017Atomic StructurePractice:1. Element D has 6 protons and 7 neutrons.Element F has 7 protons and 7 neutrons.2. Element J has 27 protons and 32 neutrons.Element L has 27 protons and 33 neutrons.3. Element X has 17 protons and 18 neutrons.Element Y has 18 protons and 17 neutrons.4. Element Q has 56 protons and 81 neutrons.Element R has 56 protons and 82 neutrons.
26 Atomic Mass Average Atomic Mass This is the mass on the Periodic Table Weighted averageOf all naturally occurring isotopesThis is the mass on the Periodic TableThis is the mass we use for calculationsCan you calculate a weighted average?
27 Atomic Mass ISOTOPE % in Nature MASS Copper-63 69.17% 62.929599 amu 100.00%
28 Atomic Mass ISOTOPE % in Nature MASS Carbon-12 98.89% 12.000 amu 100.00%