Chamras Chemistry 110 Lecture Exam 4 Materials Chapter 11 Modern Atomic Theory Rutherford s Atom: A theory developed to describe the structure of atoms, based on experimental evidence. The Experiment: Results: a) b) c) Conclusion: 1
Electromagnetic Radiation: (AKA: Light) Dual Nature: Description: Electro Magnetic Properties: Energy: Frequency: Wavelength: 2
Electromagnetic Radiation Spectrum: (A continuum) Gamma X U.V. Visible I.R. µ-wave R.F. Rays Rays Light V B G Y O R E λ ν ν E λ Relationships: E, ν, λ. Emission of Energy by Atoms: An Experiment. Sample Explanation: Energy Excited State 3
Ground State One Last Detail: Color of emitted light varies with varying sample. Explanation: Sample Line Spectrum 4
Further Insight To the Structure of Atom: Energy!Quantum Chemistry: Space is Quantized Change of Energy with Changing Distance from Nucleus: 5
Atomic Orbitals: Orbital! Space Definition: Orbital Capacity: How Is the Space Around the Nucleus Quantized? Principal Energy Levels: Orbital Types: 6
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Electron & Orbital Arrangement Around the Nucleus: Number Total Number Nucleus! of Orbitals of Electrons n=1! n=2! n=3! n=4! 8
Electron Configuration & Orbital Diagram: H: He: Li: Na: K: Be: Mg: Ca: Al: N: P: O: S: 9
Core Notation for Electron Configuration: Examples: 10
Blocks of the Periodic Table: PERIODIC TABLE IA 11
Types of Electrons: a) b) 12
Periodic Trends: a) Electronegativity: Definition: Trend: Three Most Electronegative Elements: Electronegativity:! b) Atomic Size: Trend: c) Metallic Properties: Examples of Metallic Properties: Trend: 13
d) Ionization Energy: Definition: Trend: Review: Types of Chemical Bonds: a) Chapter 12 Chemical Bonding b) Types of Chemical Compounds: a) b) 14
Bonding Spectrum: 100:0 Sharing 50:50 Sharing Measurement of Bond Polarity: Examples: H Cl H H Cl Cl Insight on the Charges of Different Ions: Remember: Valence and Core Electrons 15
Electron Configurations: He: Ne: Ar: Na + : Cl : Ca 2+ : Main Objective in Bonding (Ionic or Covalent): Examples: Ionic Bonding: Covalent Bonding: 16
Lewis Structure: A Drawing Tool Elements: Monatomic Ions: Ionic Compounds: Lewis Structures for Molecules Steps: 1. Determine the total number of valence electrons. 2. Establish the basic structural connectivity. 3. Fill in the remaining electrons. 4. Check for the octet (duet) rule. Bonding Electrons and Non-Bonding Electron Pairs (AKA: Lone Pairs) Example: 17
Diatomic Examples: Simple Examples: Choosing the central atom: Question: ***What if the Valence Electrons are Maxed Out & there are elements with an Unsatisfied Octet? 18
Multiple Bonds Example: CO 2 Example 2: Question: What if there are two or more ways of drawing reasonable Lewis structures? Resonance Example: NO 3 - More Examples: 19
Molecular Geometry Use VSEPR theory to draw the correct molecular geometry: VSEPR Theory: Examples: a) No lone pair on the central atom: Example Molecular Geometry Bond Angles CO 2 : BF 3 : CH 4 : b) 1 Lone pair on the central atom: Example Molecular Geometry Bond Angles O 3 : NH 3 : 20
c) 2 Lone pairs on the central atom: Example Molecular Geometry Bond Angles H 2 O: Chapter 13 Gases Remember: Some properties of gases Two ways to specify the amount of a sample of a gas: a) moles (n) Example: b) pressure (P), volume (V), and temperature (T) Example: 21
Pressure of Gases Definition for pressure: Equation for Pressure: Units for Pressure Conversions: Atmospheric Pressure: Demo: Atmospheric Pressure on a can of soda. 22
Temperature Volume 23
Relationships between Pressure, Temperature and Volume of Gases a) Boyle s Law: at Constant Temperature Sample Problems: 1. If the pressure of a gas increases from 6.7 atm to 12,000. Torr, how does its volume change from an original value of 3.50 liters at constant temperature 2. If the volume of a gas is quadrupled, how does its pressure change? 24
b) Charles s Law: at Constant Pressure Sample Problems: 1. If the temperature of a gas changes from 100.0K to 100.0 o C, determine the original volume of this gas if the final volume is 25.0 ml. Assume constant pressure. 2. If the temperature of a gas is doubled, how does its volume change at constant pressure? 25
c) Avogadro s Law: d) Combined Gas Law: Sample Problems: 1. A sample of a gas has 4.50liters of volume, at 750.0mmHg and 220.0 o C. Calculate the new temperature of this sample if the pressure is decreased to 0.600 atm, and the volume is increased to 6.60 liters: 26
2. If the pressure of a gas is doubled and the volume is tripled, how does the temperature change? e) Ideal Gas Law: P. V = n. R. T P = V = n = R = T = 27
Derivation: Sample Problems: 1. 2. 28
STP Molar Volume at STP When to use: Combined Gas Law: Ideal Gas Law: Molar Volume: 29
Gas Stoichiometry Given the P, V, and T of a gas involved in a chemical reaction, the n could be calculated. Stiochiometric Diagram Revised & Improved: mass of A mass of B molar mass molar mass of A of B PV=nRT mol:mol PV=nRT Volume of moles of A moles of B Volume of A(g) ratio B(g) avogadro s # avogadro s # particles of A particles of B Sample Problem 1: H 2 (g) + N 2 (g) NH 3 (g) If the reaction is carried out at 780.0torr and 400.0K, and 6.0L of hydrogen reacts with 9.0L of nitrogen, what is the volume of the ammonia gas that is expected to be produced? 30
Sample Problem 2: CaCO 3 (s) CaO(s) + CO 2 (g) Quicklime, CaO, is produced by heating calcium carbonate, CaCO 3. Calculate the volume of CO 2 expected to be produced, at STP, from the complete decomposition of 152.0 grams of calcium carbonate. Sample Problem 3: CaCO 3 (s) CaO(s) + CO 2 (g) Quicklime, CaO, is produced by heating calcium carbonate, CaCO 3. Calculate the volume of CO 2 expected to be produced, at 450.0K and 1200. mmhg, from the complete decomposition of 152.0 grams of calcium carbonate. 31