REVIEWING MAIN IDEAS 1. What is a chemical bond? 2. Identify and define the three major types of chemical bonding. 3. What is the relationship between electronegativity and the ionic character of a chemical bond? 4. a. What is the meaning of the term polar as applied to chemical bonding? b. Distinguish between polar-covalent and nonpolar-covalent bonds. 5. In general, what determines whether atoms will form chemical bonds? __ PRACTICE PROBLEMS 6. Determine the electronegativity difference, the probable bond type, and the more-electronegative atom with respect to bonds formed between the following pairs of atoms. (Hint:See Sample Problem A.) a. Hand I b. Sand O C. Kand Br d. Si and Cl e. Kand Cl f. Se and S g. Cand H 7. List the bonding pairs described in item 6 in order of increasing covalent character. Use orbital notation to illustrate the bonding in each of the following molecules: a. chlorine, Cl_(2) b. oxygen, O_(2) C. hydrogen fluoride, HF 9. The lattice energy of sodium chloride, NaCl, is -787.5kJ/mol. The lattice energy of potassium chloride, KCl, is -715kJ/mol. In which compound is Chapter 6 muleterler Gompounds REVIEWING MAIN IDEAS 10. What is a molecule? 11. a. What determines bond length? b. In general, how are bond energies and bond lengths related? 12. Describe the general location of the electrons in covalent bond. 13. As applied to covalent bonding, what is meant by a unshared or lone pair of electrons? 14. Describe the octet rule in terms of noble-gas contip rations and potential energy. 15. Determine the number of valence electrons in as atom of each of the following elements: a. H b. F C. Mg d. O e. Al f. N B. C 16. In a Lewis structure, which atom is usually the central atom? 17. Distinguish between single double, and triple covalent bonds by defining each and providing is illustration of each type. 18. For Lewis structures, how is the need for multiple bonds generally determined? __ PRACTICE PROBLEMS 19. Use Lewis valence electron dot structures to expres the arrangement of valence electrons present in cot atom of each of the following elements. (Hint: Set Sample Problem B.) a. Li e. C b. Ca f. p C. Cl g. Al d. 0 h.S

REVIEWING MAIN IDEAS<br /><br />1. A chemical bond is a force that holds atoms together in a molecule. It can be a result of sharing, donating, or accepting electrons between atoms.<br /><br />2. The three major types of chemical bonding are:<br /> - Ionic bonding: This occurs when one atom donates electrons to another atom, resulting in the formation of ions. The positively charged ion is attracted to the negatively charged ion, forming a bond.<br /> - Covalent bonding: This occurs when two atoms share electrons to form a bond. The shared electrons are equally distributed between the two atoms, resulting in a stable bond.<br /> - Metallic bonding: This occurs between metal atoms, where electrons are delocalized and shared among many atoms, resulting in a bond.<br /><br />3. Electronegativity is a measure of an atom's ability to attract shared electrons in a chemical bond. The higher the electronegativity, the more an atom attracts shared electrons. The ionic character of a chemical bond is determined by the difference in electronegativity between the two atoms. If the difference is large, the bond is more ionic, while a smaller difference results in a more covalent bond.<br /><br />4. a. In chemical bonding, the term "polar" refers to a bond where the electrons are not equally shared between the two atoms. One atom attracts the shared electrons more strongly, resulting in a partial positive charge on that atom and a partial negative charge on the other atom.<br /> b. Polar-covalent bonds occur when there is a moderate difference in electronegativity between the two atoms, resulting in an unequal sharing of electrons. Nonpolar-covalent bonds occur when the electronegativities of the two atoms are similar, resulting in an equal sharing of electrons.<br /><br />5. Atoms will form chemical bonds when they achieve a stable electron configuration, typically resembling the nearest noble gas configuration. This stability is achieved by sharing, donating, or accepting electrons to complete their outermost electron shell.<br /><br />PRACTICE PROBLEMS<br /><br />6. <br /> a. Electronegativity difference: 0.9, Bond type: Nonpolar covalent, More electronegative atom: I<br /> b. Electronegativity difference: 0.8, Bond type: Polar covalent, More electronegative atom: O<br /> c. Electronegativity difference: 0.7, Bond type: Polar covalent, More electronegative atom: Br<br /> d. Electronegativity difference: 0.4, Bond type: Polar covalent, More electronegative atom: Cl<br /> e. Electronegativity difference: 0.8, Bond type: Ionic, More electronegative atom: Cl<br /> f. Electronegativity difference: 0.1, Bond type: Nonpolar covalent, More electronegative atom: Se<br /> g. Electronegativity difference: 2.1, Bond type: Ionic, More electronegative atom: C<br /><br />7. <br /> a. $Cl_{2}$: Both chlorine atoms have the same electronegativity, resulting in a nonpolar covalent bond.<br /> b. $O_{2}$: Both oxygen atoms have the same electronegativity, resulting in a nonpolar covalent bond.<br /> c. HF: Fluorine is more electronegative than hydrogen, resulting in a polar covalent bond.<br /><br />9. The lattice energy of sodium chloride, NaCl, is $-787.5kJ/mol$, while the lattice energy of potassium chloride, KCl, is $-715kJ/mol$. Since the lattice energy of NaCl is more negative, it indicates that NaCl has a stronger ionic bond compared to KCl. This is because sodium is smaller and more charged than potassium, resulting in a stronger attraction between the ions.<br /><br />10. A molecule is a group of atoms bonded together, representing the smallest unit of a chemical compound that retains its chemical properties.<br /><br />11. <br /> a. Bond length is determined by the size of the atoms involved and the strength of the bond. Generally, shorter bonds are stronger and have higher bond energies.<br /> b. Bond energies and bond lengths are inversely related. Shorter bonds have higher bond energies because the atoms are closer together and the bond is stronger.<br /><br />12. In a covalent bond, the electrons are shared between the two atoms. The general location of the electrons in a covalent bond is in the region between the two atoms, forming a bond cloud.<br /><br />13. A unshared or lone pair of electrons refers to a pair of electrons that are not involved in bonding. These electrons are localized on one atom and do not participate in the formation of the bond.<br /><br />14. The octet rule states that atoms tend to form stable configurations by having eight electrons in their outermost electron shell. This configuration resembles the nearest noble gas configuration, which