Bonding: General Concepts (cont’d) Chapter 8(b) Bonding: General Concepts (cont’d)

Lithium fluoride Copyright © Houghton Mifflin Company. All rights reserved.

Figure 8.8: The energy changes involved in the formation of solid lithium fluoride from its elements.

Figure 8.9: The structure of lithium fluoride.

Figure 8.10: Comparison of the energy changes involved in the formation of solid sodium fluoride and solid magnesium oxide.

Figure 8.11: The three possible types of bonds (a) a covalent bond formed between identical atoms (b) a polar covalent bond, with both ionic and covalent components; and (c) an ionic bond with no electron sharing.

Figure 8.12: The relationship between the ionic character of a covalent bond and the electronegativity difference of the bonded atoms.

Molten NaCl conducts an electric current, indicating the presence of moblie Na+ and Cl- ions.

Copyright © Houghton Mifflin Company. All rights reserved.

Copyright © Houghton Mifflin Company. All rights reserved.

Figure 8. 14: The molecular structure of methane Figure 8.14: The molecular structure of methane. The tetrahedral arrangement of electron pairs produces a tetrahedral arrangement of hydrogen atoms.

Figure 8.15:(a) The tetrahedral arrangement of electron pairs around the nitrogen atom in the ammonia molecule. (b) Three of the electron pairs around nitrogen are shared with hydrogen atoms as shown and one is a lone pair. Although the arrangement of electron pairs is tetrahedral, as in the methane molecule, the hydrogen atoms in the ammonia molecule occupy only three corners of the tetrahedron. A lone pair occupies the fourth corner. (c) Note that molecular geometry is trigonal pyramidal, not tetrahedral. Copyright © Houghton Mifflin Company. All rights reserved.