Models Models are attempts to explain how nature operates on the microscopic level based on experiences in the macroscopic world. Copyright © Cengage Learning.

Slides:



Advertisements
Similar presentations
VSEPR and Molecular Geometry
Advertisements

Page 34 In a chemical reaction, bonds in the reactants are broken and the atoms rearrange to form new bonds in the products. Flames or heat associated.
Chapter 4 Bonding: General Concepts. Chapter 8 Table of Contents 4.1 Types of Chemical Bonds 4.2 Electronegativity 4.3 Bond Polarity and Dipole Moments.
Check your answers for Lewis Structures with one another. Make sure you all come to a consensus of the correct answers for each. Make sure you handed in.
Bond Enthalpy L.O.:  Explain exothermic and endothermic reactions in terms of enthalpy changes associated with the breaking and making of chemical bonds.
Unit 2, Module 3, Energy Bond Enthalpies Thursday, 02 July 2015.
Chapter 8 Bonding: General Concepts. Section 8.1 Types of Chemical Bonds Copyright © Cengage Learning. All rights reserved 2 A Chemical Bond  No simple,
Exothermic and Endothermic Reactions. Exothermic reactions An exothermic reaction is a chemical change that releases energy. Where does the energy that.
Resonance Resonance is invoked when more than one valid Lewis structure can be written for a particular molecule. The actual structure is an average of.
Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Bonds Forces that hold groups of atoms together and make them function as a unit. Bonds.
2.4 Chemical Reactions TEXTBOOK PAGES KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
Chapter 9 Lecture Basic Chemistry Fourth Edition 9.5 Energy in Chemical Reactions Learning Goal Given the heat of reaction (enthalpy change), calculate.
Thermochemical Equations
Chemical Reactions, cont’d. Absorbs energyReleases energy Endothermic Reaction Exothermic Reaction.
Chem Notes Ionic bonds=high melting point, high boiling point, brittle, high electrical conductivity in molten state or in aqueous state.
Models Models are attempts to explain how nature operates on the microscopic level based on experiences in the macroscopic world. Models can be physical.
ENERGY EXCHANGES IN CHEMICAL REACTIONS
Basic Chemistry Copyright © 2011 Pearson Education, Inc. 1 Chapter 9 Chemical Quantities in Reactions 9.5 Energy in Chemical Reactions Cold packs use an.
5.4 Bond enthalpies Define the term average bond enthalpy Explain, in terms of average and enthalpies, why some reactions are exothermic and.
Heat in Chemical Reactions Ch. 16. Energy in Chemical Reactions Every reaction has an energy change associated with it Energy is stored in bonds between.
Chapter 8 - Bonding Ionic Bonding  Electrons are transferred  Electronegativity differences are generally greater than 1.7  The formation of ionic.
Bonding: General Concepts Continued.
HEAT IN CHEMICAL REACTIONS
What is meant by the term “chemical bond”?
Breaking and making bonds
Ch. 17 THERMOCHEMISTRY.
Endothermic & Exothermic Reactions
Bond Energy and Reactions
Chemical Reaction Energy
Heat and Enthalpy.
KEY CONCEPT Life depends on chemical reactions.
Energy and Chemical Reactions
KEY CONCEPT Life depends on chemical reactions.
Heat in Reactions.
Change in Enthalpy State function ΔH = q at constant pressure
KEY CONCEPT Life depends on chemical reactions.
Bond Energy and Reactions
Lesson # 3: Bond Energies
Bond Energy and Reactions
Representing Enthalpy Changes
Enthalpy of Reactions -We can describe the energy absorbed as heat at constant pressure by the change in enthalpy (ΔH) -the enthalpy of a reaction is the.
Unit 1: Reaction Kinetics
Intro to chemistry Therm o breaking forming
KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
Bonding: General Concepts Continued.
Energetics IB.
Chapter 7.1 – Nature of Chemical Reactions
Potential Energy Main Concept:
12.1 Chemical reactions that involve heat
Bond Enthalpy Chem 12.
Energy Changes.
Endothermic & Exothermic Reactions
Bond energies.
KEY CONCEPT Life depends on chemical reactions.
Bonding – General Concepts
Heat and the Enthalpy of Reaction
KEY CONCEPT Life depends on chemical reactions.
The Covalent Chemical Bond: A Model
Bond Energy and Reactions
Covalent Bonding: Models
KEY CONCEPT Life depends on chemical reactions.
CALCULATION OF ENTHALPY CHANGE USING BOND ENERGY
Resonance Resonance is invoked when more than one valid Lewis structure can be written for a particular molecule. Benzene, C6H6 The actual structure is.
KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
KEY CONCEPT Life depends on chemical reactions.
Presentation transcript:

Models Models are attempts to explain how nature operates on the microscopic level based on experiences in the macroscopic world. Copyright © Cengage Learning. All rights reserved

Fundamental Properties of Models A model does not equal reality. Models are oversimplifications, and are therefore often wrong. Models become more complicated and are modified as they age. We must understand the underlying assumptions in a model so that we don’t misuse it. When a model is wrong, we often learn much more than when it is right. Copyright © Cengage Learning. All rights reserved

Bond Energies To break bonds, energy must be added to the system (endothermic, energy term carries a positive sign). To form bonds, energy is released (exothermic, energy term carries a negative sign). Copyright © Cengage Learning. All rights reserved

Bond Energies Enthalpy =S [moles×D (bonds broken)] – S[moles×D (bonds formed) ] D represents the bond energy per mole of bonds (always has a positive sign). Copyright © Cengage Learning. All rights reserved

Given the following information: Bond Energy (kJ/mol) C–H 413 C–N 305 CONCEPT CHECK! Predict DH for the following reaction: Given the following information: Bond Energy (kJ/mol) C–H 413 C–N 305 C–C 347 891 [3(413) + 305 + 891] – [3(413) + 347 + 891] = –42 kJ ΔH = –42 kJ Copyright © Cengage Learning. All rights reserved

Feedback: Privacy Policy Feedback
Do Not Sell My Personal Information
About project: SlidePlayer Terms of Service

© 2025 SlidePlayer.com. Inc. All rights reserved.