Unit 8 Notes 1 Molecules Law of Definite and Multiple Proportions Law of Conservation of Mass Dalton’s Atomic Theory Calculating Average Atomic Mass

Laws of Proportions What is the proportion for? H2O H2O2 N2O3 2:1 N2O5 Definite Proportions 2:1 1:1 2:3 Multiple Proportions 2:5 2:1 1:2

Law of Conservation of Mass 2H2(g) + 1O2(g)→2H2O(l) H = 2 x 2.0 = 4.0 O = 1 x 32.0 = 32.0 H = 2 x 2.0 = 4.0 O = 2 x 16.0 = 32.0 + + 36.0 36.0 3H2(g) + 1N2(g)→2NH3(l) N = 2 x 14.0 = 28.0 H = 2 x 3.0 = 6.0 N = 1 x 28.0 = 28.0 H = 3 x 2.0 = 6.0 + + 34.0 34.0 2C2H6(g)+ 7O2(g)→ 4CO2(g) + 6H2O(l) C = 2 x 24.0 = 48.0 H = 2 x 6.0 = 12.0 O = 7 x 32.0 = 244.0 C = 4 x 12.0 = 48. 0 H = 6 x 2.0 = 12.0 O = (4 x 32.0) + (6 x16.0) = 244.0

Three laws that support the existence of atoms 1. Law of Definite Proportions 2. E=MC2 3. Law of Multiple Proportions 4

Principles of Dalton's Atomic Theory 1. All matter is made of indivisible and indestructible atoms. 2. All atoms of a certain element are identical in mass and properties. 3. Compounds can be formed by using two or more different kinds of atoms. 4. A chemical reaction is a rearrangement of atoms. 5

Carbons Mass in amu and gram units 1 amu=1/12 C-12 1 C-12 mass = 12.00000000 amu 1 amu = 1.66053X10-24 grams. 12.0000000 grams/Mole! 6

Calculating Average Atomic Mass E amu % product C-12 12.000000 x 98.90 = 1186.8 C-13 13.003355 x 1.10 = 14.3036905 1187 1187 98.90 % + 14.3 + 14 + 1.10 % 1201 100.00 % 1201 ÷100.00 = 12.01amu 4 sd 5 sd 4 sd 7

Unit 8 Notes 2 The Nucleus Review of Average Atomic Mass Cathode Ray Varies Experiments Nuclear Reactions Atomic Particles 8

Calculating Average Atomic Mass E amu % product 79Br 78.9183376 x 50.697 = 4000.922961 = 3990.548738 81Br 80.9162913 x 49.317 4000.9 50.697 % + 3990.5 +49.317 % 7991.4 100.014 % 7991.4 ÷100.014 = 79.9028136 amu 5 sd 6 sd 5 sd = 79.903 amu

Cathode Ray Electrons(e-1) go toward the anode - + e-1→ e-1→ e-1→ e-1→ Examples: TV and Computer Monitor

Cathode Ray Devices 11

Van de Graff ←Leyden Jar Van de Graff generator➔

Millikan's oil-drop experiment Charge of e-1 is equal to -1.602189 x 10-19 Coulombs. Oil drops→ ← perfume sprayer hole→ ← (+) plate . -2 . -1 X-ray→ . battery→ ← (-) plate 13

Rutherford's experiments Alpha particle→ Lead Radium→ α+2 8000 α → Microscope→ 7999 α pass through 42He+2 Gold Foil↑ 10,000 atoms thick α+2 Characteristics of atoms mostly empty space +79 Small(1/10,000), dense, and heavy positive charge core 14

Atoms and their electrons, protons, and neutrons Proton(P+1) + Neutrons(n0)= Mass #(Z) Isotope Name = Element – Mass # A Z Element P+1 n0 Symbol Name 1 1 1 Hydrogen 1 H Hydrogen -1 1 1 2 Hydrogen 1 1 H 2 Hydrogen -2 1 1 3 Hydrogen 1 2 H 3 Hydrogen -3 1 8 16 Oxygen 8 8 O 16 Oxygen -16 8 26 57 Iron 26 31 Fe 57 Iron -57 26

Nuclear Reactions U + n → Xe + Sr + n n+ Li → H + He + n U → Th + He β A reaction, as in fission, fusion, or radioactive decay, that alters the energy, composition, or structure of an atomic nucleus. Fission: 235 U + 1 n → 135 Xe + 100 Sr + n 1 92 54 38 Fusion: 1 n+ 7 Li → 3 H + He + 4 1 n 3 1 2 Decay: 238 U → 234 Th + 4 He Alpha Decay 92 90 2 β 234 Th → 234 Pa + Beta Decay(e-1) 90 91 -1

Atomic Particles In an atom, the nucleus is about 10-15 in size Symbol Charge Mass (g) Mass (amu) proton p+ +1 1.673 x 10-24 1.00727 neutron n0 1.675 x 10-24 1.00866 electron e- -1 9.109 x 10-28 5.485 x 10-4 In an atom, the nucleus is about 10-15 in size A proton is about 1835x more massive than an electron

Unit 8 Notes 3 Electron Arrangements for Elements De Broglie’s Wave Model Orbital Shapes State Pauli's exclusion Principle, the aufbau principle, and Hund's rule. Orbital Filling Diagrams

De Broglie’s Wave Model for Electrons Wave Nature Different solutions for e-1 actions. e-1’s act as a particle or a wave. e-1’s absorb or release Quantum Amount of NRG. Demo of waves on a string

S Orbital y-axis z-axis X-axis

P Orbitals Shapes x-axis y-axis z-axis

p Orbitals Assembled y-axis z-axis x-axis

Quantum Model for The Shell of The Atom

Electron Order of Filling Aufbau Principle - Fill the lowest energy level first Hund’s Rule - Everything is paired up last Pauli Exclusion Principle - Spins are always opposite

Orbital Filling Diagram Write the orbital filling diagram for Ne. How many electrons does Ne have? Final Answer Shorthand Answer 10 e-1 ↑ ↑ ↑ ↑ ↑ ↑ 1s 2 2s 2 2p 6 ↑ ↑ [He] 2s 2 2p 6 ↑ ↑ 26

Orbital Filling Diagram Write the orbital filling diagram for Na. How many electrons does Na have? Final Answer Shorthand Answer 11 e-1 ↑ ↑ ↑ ↑ ↑ ↑ ↑ 1s 2 2s 2 2p 6 3s 1 ↑ ↑ [Ne] 3s 1 ↑ ↑ 27

Orbital Filling Diagram Write the orbital filling diagram for Cl. How many electrons does Cl have? Final Answer Shorthand Answer 17 e-1 ↑ ↑ ↑ ↑ ↑ ↑ ↑ 1s 2s 2p 3s 3p 2 2 6 2 5 ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ [Ne] 3s 3p 2 5 ↑ ↑ 28

Unit 8 Notes 4 The Structure of the Atom’s Shell Review of Atom Models Electron Dot Configuration Quantum Numbers Electromagnetic Spectrum

Thompson Model Negative electrons on the positive surface Atoms mass is positively charged and widely spread. Electrons don’t move, unless releasing energy. Ex. Chocolate Chips in Ice Cream

Rutherford Model *Mostly Empty Space *Nucleus… Very Small Very Dense + Positive Charged Where were the electrons? What are the electrons doing?

Neil Bohr Model e-1 found in the empty space. He used light to define their actions. e-1 region +

Electromagnetic Spectrum Visible Light gamma ray Short wave X-ray UV IR radar FM TV AM Short wavelength Long wavelength High Energy Low Energy 33

Bohr’s Model of the shell *Particle Model *Circular orbits *Hydrogen only e-1 Light’s Energy

Electron Dot Diagram for Neon [He] 2s 2 2p 6 ↑ ↑ ↑ ↑ ↑ ↑ ● ● ↑ Ne ↑ ● ● ● ● ● ● ↑ ↑ 35

Electron Dot Diagram for Sodium [Ne] 3s 1 ↑ Na ● ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ 36

Electron Dot Diagram for Chlorine 3s 2 3p 5 ↑ ↑ ↑ ↑ ↑ ● ● Cl ↑ ↑ ● ● ● ● ↑ ↑ ↑ ● ↑ ↑ ↑ ↑ ↑ ↑ ↑

Quantum Numbers Addresses for electrons Four numbers for each address No two addresses are the same First number is n =1 , 2 , 3 , 4 , 5 , 6 , 7 (Distance From the Second number is l = 0 , 1 , 2 , 3 Nucleus) s p d f Third number is ml = 0 s orbital = +1, 0, -1 p orbital = +2, +1, 0, -1, -2 d orbital = +3, +2, +1, 0, -1, -2 , -3 f orbital Forth number is ms = +1/2 or -1/2

Quantum Numbers ms = +1/2 or -1/2= n= 3 l= 1 ml = ms = -1/2 ↑ ↑ ↑ ms = +1/2 or -1/2= n= 3 l= 1 ml = ms = -1/2 l = 0(s), 1(p), 2(d), 3(f) =

Quantum Numbers ms = +1/2 or -1/2= n= 7 l= ml = ms = +1/2 ↑ ↑ ↑ ms = +1/2 or -1/2= n= 7 l= ml = ms = +1/2 l = 0(s), 1(p), 2(d), 3(f) =

Quantum Numbers ↑ n= 4 l= 3 ml = +2 ms = -1/2

Quantum Number for Last e-1 in In → → → → → → What element are we looking for? → → → → → → → What block is it in? How many into the block is it? Where does the final arrow fall? Quantum #’s for Last e-1 n= 5 l= 1 ml= +1 ms= +1/2 42

Unit 8 Notes 5 Spectroscope Analyzing Spectrums

The Spectroscope Prism slit Bright-line Emission Spectrum Helium Tube spectrograph

Solar Spectrum➔ (92 elements) hydrogen➔ helium➔ mercury➔ uranium➔

Spectrum Example #1 n=6 n=5 n=4 Excited State n=3 n=2 Quantum Amount Violet indgo Blue Green Yellow Orange Red n=5 n=4 Excited State n=3 n=2 Quantum Amount n=1 Ground State energy

Spectrum Example #2 n=6 n=5 n=4 Excited State n=3 n=2 Quantum Amount Violet indgo Blue Green Yellow Orange Red n=5 n=4 Excited State n=3 n=2 Quantum Amount n=1 Ground State energy

Spectrum Example #3 n=6 n=5 n=4 Excited State n=3 n=2 Quantum Amount Violet indgo Blue Green Yellow Orange Red n=5 n=4 Excited State n=3 n=2 Quantum Amount n=1 Ground State energy