CHM1045 Lecture 4Outline of Last LectureI. Dimensional Analysis Method of Solving ProblemsOutline of Current LectureI. Daltons Atomic Theory:II. Cathode Ray TubeIII. Millikan’s Experiment:IV. Rutherford’s ExperimentV. Chadwick’s ExperimentVI. Atomic#/Mass #/IsotopesVII. MoleculesVIII. IonsCurrent LectureDaltons Atomic Theory:1. Elements are composed of extremely small particles Called atoms2. All atoms of a given element are identical, having the same size, mass and chemicalproperties. The atoms of one element are different from the atoms of all other elements.3. Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction.4. A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destructionEx. Carbon Monoxide: O/C = 1/1 Carbon Dioxide: O/C= 2/1 Law of Multiple Proportions Ex. 16 X+ 8 Y 8 X2YLaw of Conservation of MassCathode Ray Tube- shooting an electron to show it’s negative changeMillikan’s Experiment:- They could measure the mass of the electronE=-1.60*10-19CRutherford’s Experiment- Shot a positive particles and a gold foil- Shows that the nucleus isn’t organized- Proton has opposite charge then electron - Small volume in atomChadwick’s Experiment- Found that HE had neutrons also- H-1 H-2- Found that the neutron has no charge- Contains neutrons equal in mass to protonsAtomic#/Mass #/Isotopes1. Atomic Number (Z) = # of protons in the nucleus2. Mass Number(A)= # of protons plus neutronsAtomic # + # of neutrons3. Isotopes= atoms of the same element (X) with different number of neutrons in nucleiXAZExample 1: How many protons, electrons, and neutrons are in the following:a. NA2011 = 11 protons,11 electrons, (20-11) 9 neutronsb. NA2211 = 11 protons, 11 electrons, (22-11) 11 neutronsc. O17 = 8 protons, 8 electrons, (17-8) 9 neutronsd. Carbon -14 = C146 6 electrons, 6 protons, 8 neutronsReview:• Which of the following two symbols provides more information?17O or O 8 ? 17O because its provides more information then 8OMolecule:- Molecule: is an aggregate of two or more atoms in a definite arrangement held together by chemical forces. Ex. H2O,NH3- Diatomic molecule- contains only two atomsEx. H2,N2, O2- Polyatomic molecule- contains more than two atoms:Ex. O3, H2O, NH3, CH4Ions:Ion- is an atom, or group of atoms, that has a net positive or negative chargeCation – ion with a positive chargeIf a neutral atom loses one or more electrons it becomes a cation.Na- 11 protons and 11 electrons Na+ - 11 protons and 10 electronsanion – ion with a negative chargeIf a neutral atom gains one or more electrons it becomes an anion.Cl- 17 protons and 17 electrons Cl- : 18 electrons and 17 protonsmonatomic ion: contains only one atom: Na+, Cl-, Ca2+, O2-, Al3+, N3-polyatomic ion: contains more than one atom: OH-, CN-, NH4+,
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