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. Whatis 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 the bonding between ions stronger? Why? 206 Chapter 6

2. The three major types of chemical bonding are:<br /><br />a. Ionic Bonding: This type of bonding occurs when there is a transfer of electrons from one atom to another, resulting in the formation of ions. The bond is formed due to the electrostatic attraction between the positively charged cation and the negatively charged anion.<br /><br />b. Covalent Bonding: In covalent bonding, atoms share electrons to achieve stability. This type of bonding can be further classified into two categories:<br /><br />- Nonpolar Covalent Bonding: This occurs when the electrons are shared equally between the atoms, resulting in a balanced distribution of charge. Nonpolar covalent bonds are typically found in molecules composed of identical atoms.<br /><br />- Polar Covalent Bonding: This type of bonding occurs when the electrons are not shared equally between the atoms. One atom attracts the shared electrons more strongly, resulting in an unequal distribution of charge. Polar covalent bonds are found in molecules where there is a difference in electronegativity between the bonded atoms.<br /><br />c. Metallic Bonding: Metallic bonding occurs when there is a delocalization of electrons within a lattice of metal atoms. The electrons are free to move throughout the structure, giving rise to a "sea of electrons" that are shared among all the atoms in the metal. This type of bonding is responsible for the characteristic properties of metals, such as conductivity and malleability.<br /><br />3. Electronegativity is a measure of an atom's ability to attract shared electrons in a chemical bond. The relationship between electronegativity and the ionic character of a chemical bond is that the greater the difference in electronegativity between the two atoms, the more ionic the bond will be. In an ionic bond, one atom donates electrons to the other, resulting in the formation of ions with opposite charges. The stronger the electronegativity difference, the more likely the bond will be ionic.<br /><br />4. a. In the context of chemical bonding, the term "polar" refers to a bond or molecule that has an unequal distribution of charge. This occurs when there is a difference in electronegativity between the bonded atoms, resulting in a partial positive charge on one atom and a partial negative charge on the other.<br /><br />b. Polar covalent bonds and nonpolar covalent bonds differ in the way electrons are shared between the atoms:<br /><br />- Polar Covalent Bond: In a polar covalent bond, the electrons are shared unequally between the atoms. One atom attracts the shared electrons more strongly, resulting in an unequal distribution of charge. This leads to the formation of partial charges on the atoms, giving the bond a polar character.<br /><br />- Nonpolar Covalent Bond: In a nonpolar covalent bond, the electrons are shared equally between the atoms. There is no significant difference in electronegativity between the bonded atoms, resulting in a balanced distribution of charge. Nonpolar covalent bonds are typically found in molecules composed of identical atoms or molecules with a symmetrical shape.<br /><br />5. The formation of chemical bonds between atoms is generally determined by the desire to achieve stability. Atoms tend to form bonds in order to attain a stable electron configuration, which is often associated with having a full outermost energy level. This stability can be achieved through the sharing or transfer of electrons, depending on the type of bonding involved.<br /><br />6. To determine the electronegativity difference, the probable bond type, and the more electronegative atom for each pair of atoms, we can refer to the Pauling electronegativity values:<br /><br />a. H and I: Electronegativity difference = 2.66 - 2.20 = 0.46. The bond is likely to be a polar covalent bond, with iodine being the more electronegative atom.<br /><br />b. S and O: Electronegativity difference = 3.44 - 2.55 = 0.89. The bond is likely to be a polar covalent bond, with oxygen being the more electronegative atom.<br /><br />c. K and Br: Electronegativity difference = 2.96 - 0.82 = 2.14. The bond is likely to be an ionic bond, with bromine being the more electronegative atom.<br /><br />d. Si and Cl: Electronegativity difference = 3.16 - 1.90 = 1.26. The bond is likely to be a polar covalent bond, with chlorine being the more electronegative atom.<br /><br />e. K and Cl: Electronegativity difference = 3.16 - 0.82 = 2.34. The bond is likely to be an ionic bond, with chlorine being the more electronegative atom.<br /><br />f. Se and S: Electronegativity difference = 2.55 - 2.58 = -0.03. The bond is likely to be a nonpolar