PS 11 key - Recitation PDF

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Problem Set 11 – Bonding Chem 105 1. (a) What is a chemical bond? Electrostatic attraction that keeps two atoms close together (b) Why do atoms form bonds? To minimize energy; being in close proximity results in a lower energy state for both atoms 2. Define the following types of bonds: a. Ionic: a bond resulting from the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions) b. Covalent: bond resulting from electrostatic attraction between the positively charged nuclei of two atoms and the negatively charged electrons that are shared between them A) Polar covalent: covalent bond in which the electrons are NOT shared equally B) Non-polar covalent: covalent bond in which the electros are shared equally c. Metallic: a bond resulting from the electrostatic attraction of the nuclei of metal atoms to the sea of shared electrons from each atom 3. (a) Define electronegativity in your own words. Ability of an atom to pull electrons in a bond toward itself (b) 4.79 How can we use electronegativity to predict whether a bond between two atoms is likely to be covalent of ionic? When a large difference in electronegativity exists, the transfer of an electron from one atom to another is likely and an ionic bond will form. When electronegativities of two atoms are similar, the electrons will be shared in a covalent bond. The general rule is that if an electronegativity difference of 2.0 or greater is present, the bond between the atoms will be ionic. 4. What type of bonds are expected in the following materials? a) Oxygen non-polar covalent b) NaCl ionic c) H2O polar covalent d) Diamond (pure carbon) non-polar covalent e) Methane (CH4) non-polar covalent f) Tin metallic g) Iodine non-polar covalent h) Carbon monoxide polar covalent i) NO2 polar covalent j) Mercury metallic 5. 5.49 The compound COCl2 has been used as a chemical warfare agent. It and two similar compounds, COBr2 and COI2, are all eye irritants and cause skin to blister. The severity of the skin reactions is influenced by the polarity of the compounds. Rank the compounds in order of increasing polarity of their carbon-halogen bonds. COI2, COBr2, COCl2 6. 5.54 Among the diatomic molecules detected in interstellar space are CO, CS, SiO, SO, and NO. Arrange the molecules in order of increasing polarity. Bond polarity depends on the difference in electronegativity of the atoms. Using the difference in electronegativity values for each of the atoms, we obtain the following order of increasing polarity: CS (∆EN=0) < NO (∆EN = 0.5) < SiS (∆EN=0.7) < SO = CO (∆EN=1.0) < SiO(∆EN=1.7)...