301 Exam 2 Help Sheet - CH 301 50970 Exam 2 Study Sheet Dr....

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CH 301 50970 Exam 2 Study Sheet Dr. Quy MWF 2:00 – 3:00 pm Chapter 13 Bonding: General Concepts Chapter 14 Covalent Bonding: Orbitals (14.1 Hybridization and the Localized Electron Model) Types of Chemical Bonds Bonds are forces that hold two or more atoms together. Bonds form in order that atom systems can find the lowest possible state of energy. Bond energy is the energy required to break a bond. Identify a bond as covalent, polar covalent, or ionic. Be able to apply these (and all) concepts to real-world or hypothetical issues. Periodic Trends. Explain periodic trends and exceptions to the trends. Compare (or rank) substances per periodic trends, especially electronegativity and atom and ion size. Know how to describe charge density on an ion (charge/size.) Ionic Bonds result when an electron is transferred from one atom to another, generally when a metal reacts with a non-metal. Electrostatic forces constitute ionic bonds, with strength according to Coulomb’s law which applies only to ion pairs in the gas phase. Learn to recognize the form of Coulomb’s law. No compound may be entirely ionic in the gas phase, but they are in the solid (crystalline) phase. % ionic character of a bond is calculated by (measured dipole moment of X-Y)/(calculated dipole moment of X + Y - ). Lattice energy is the change in energy that takes place when separated gaseous ions are packed together to form an ionic solid. Overall change in energy includes the energy to form the separated gas ions from their most stable neutral state and is the sum of the changes including lattice energy. The magnitude of lattice energy depends on ion charge densities which in turn determine the salt’s melting point. Compare or rank the relative lattice energies among a given set of ionic compounds. Covalent Bonds result when atoms share electrons. Polar covalent bonds occur when one atom in the bond has a greater attraction for the shared electrons (electronegativity) but not enough to effect full transfer. Calculate the difference in electronegativity for a given bond. Covalent bond energies. The bond energies required to break a bond are positive (endothermic) and are give that way in tables of bond energies. The enthalpy of formation for a given reaction is given by Δ H = Σ Bonds Broken – Σ Bonds Formed. Know the difference between single, double and triple bonds.
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301 Exam 2 Help Sheet - CH 301 50970 Exam 2 Study Sheet Dr....

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