Electrons transferred, Electrons shared NO – # unpaired electrons = #electrons alone in orbital creating ions IONS! C has 2 unpaired electrons Forms crystal lattice A few form covalent K has 1, Ag has 1, Pb has 2, Mn has 5, Mg has 0 And thus networks (SiO2, , most Unpaired electrons make element paramagnetic. crystals form individual molecules Drawing Lewis Structures for COVALENT compounds: Formula units molecules The atom with lowest EN is the central atom. Higher MP, Higher BP Lower MP, lower BP Count the total number of valence electrons. (must break bond to (only break IMFS NOT MAGIC NUMBER! (adjust for ions) change phase) bonds to change phase) Place one sigma bond (a pair of electrons) Lattice Energy Bond energy between each pair of bonded atoms. Higher charge, smaller Higher bond smaller Subtract the total number of valence electrons size= stronger bond atom = stronger bond used for bonds from the MAGIC NUMBER. Forms polar and nonpolar Place lone pairs about each terminal atom bonds except for hydrogen atoms. Subtract the EN difference Medium (polar) or Small number of lone pairs from the sum. (nonpolar) EN difference If e- are still left at this point, assign them to the If soluble, forms Nonelectrolytes, may central atom. If the central atom is from the electrolytes when dissolve but won’t ionize! third or a higher period, it can accommodate dissolved more than four pairs of electrons. Electrolytic when Nonelectrolyte If the central atom is not yet surrounded by four molten, not solid electron pairs, convert one or more terminal High % ionic character Low % ionic character atom lone pairs to pi bond pairs. COVALENT Metal + nonmetal Nonmetal + nonmetal Metal +polyatomic ion Within poly ion Poly ion + nonmetal Poly ion + poly ion Strongest type of bond Weaker bond Show resonance! Electrostatic attraction Electrostatic attraction between oppositely between nuclei and charged ions shared electrons Total Shape Atoms Lone Molecular Picture Hybridization Symmetrical in Example of a number of bonded on 3d Lewis structure And bond angles sigma to central central that is this bonds and atom atom shape. (Yes, lone pairs (# of draw the Lewis on central bonds) structure!) atom 2 Linear 2 0 sp yes 3 Triangular 3 0 sp2 yes Planar 3 Bent 2 1 sp2 no
# unpaired electrons = #electrons alone in orbital C has 2 unpaired electrons K has 1, Ag has 1, Pb has 2, Mn has 5, Mg has 0 Unpaired electrons make element paramagnetic. Drawing Lewis Structures for COVALENT compounds: The atom with lowest EN is the central atom. Count the total number of valence electrons. MAGIC NUMBER! (adjust for ions) Place one sigma bond (a pair of electrons) between each pair of bonded atoms. Subtract the total number of valence electrons used for bonds from the MAGIC NUMBER. Place lone pairs about each terminal atom except for hydrogen atoms. Subtract the number of lone pairs from the sum. If e- are still left at this point, assign them to the central atom. If the central atom is from the third or a higher period, it can accommodate more than four pairs of electrons. If the central atom is not yet surrounded by four electron pairs, convert one or more terminal atom lone pairs to pi bond pairs. COVALENT Metal + nonmetal Metal +polyatomic ion Poly ion + nonmetal Poly ion + poly ion Nonmetal + nonmetal Within poly ion Strongest type of bond Weaker bond Electrostatic attraction between oppositely charged ions Electrostatic attraction between nuclei and shared electrons Electrons transferred, creating ions Electrons shared – NO IONS! Forms crystal lattice And thus crystals A few form covalent networks (SiO2, , most form individual molecules Formula units molecules Higher MP, Higher BP (must break bond to change phase) Lower MP, lower BP (only break IMFS NOT bonds to change phase) Lattice Energy Bond energy Higher charge, smaller size= stronger bond Higher bond smaller atom = stronger bond Forms polar and nonpolar bonds EN difference Medium (polar) or Small (nonpolar) EN difference If soluble, forms electrolytes when dissolved Nonelectrolytes, may dissolve but won’t ionize! Electrolytic when molten, not solid Nonelectrolyte High % ionic character Low % ionic character Show resonance! Total number of sigma bonds and lone pairs on central atom Shape Atoms bonded to central atom (# of bonds) Lone on central atom Molecular Picture And bond angles Hybridization Symmetrical in 3d Example of a Lewis structure that is this shape. (Yes, draw the Lewis structure!) 2 Linear 2 0 sp yes 3 Triangular Planar 3 0 sp2 yes 3 Bent 2 1 sp2 no
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