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Chapter 9
Chemical Bonds

9.CO
Title
Cubic crystals of table salt
Caption
Cubic crystals of sodium chloride, table salt are shown.
Keywords
salt, lattice, bonding, crystal
9.1ab
Title
Electrostatic attractions & repulsions in 2 simple molecular species
Caption
The electrostatic attractions (red) and repulsions (blue) in and H2 are described in the text.
Keywords
bonding, electrostatics
9.2
Title
Energy of interaction of 2 hydrogen atoms
Caption
The molecular models and graph together show that the lowest energy for two H atoms comes at the internuclear distance in the H2 molecule, 74 pm.
Keywords
internuclear distance, bonding, van der waals, energy, graph
9.4
Title
formation of a crystal of sodium chloride
Caption
Formation of a crystal of sodium chloride requires ionization of sodium and formation of chloride ions from chlorine.
Keywords
salt, crystal, lattice, empirical formula, ionic bonding, bonding
9.5
Title
Born-Haber cycle for 1 mol of sodium chloride
Caption
The starting point and the five steps of the cycle are shown. (DH values are not to scale.) The sum of the five enthalpy changes (DH1 to DH5) gives DHf. The equivalent one-step reaction for the formation of NaCl(s) directly from Na(s) and 1/2 Cl2(g) is shown in red.
Keywords
hess' law, born haber cycle, lattice energy, salt, enthalpy, ionizaition energy, graph, state function
9.6
Title
Four hydrogen compounds of 2nd period nonmetals
Caption
The formulas of the four molecules can be deduced from Lewis structures, but their geometrical shapes cannot. Geometric shapes of molecules can be predicted by methods presented in Chapter 10, and they can be precisely established by experiment.
Keywords
compounds, Lewis structure, periodic trends, molecular formula
9.7
Title
Paramagnetism of oxygen
Caption
Liquid oxygen is held by a magnet. This property is paramagnetism.
Keywords
paramagnetism, oxygen, lewis structure, electron, magnet, electron configuration
9.7.3
Title
Electronegativity
Caption
In the periodic table, the trend in electronegativity for elements is an increase toward the right. Electronegativities are also highest at the "top" of a group. The most electronegative element is Fluorine; the least electronegative is Francium.
Keywords
electronegativity, periodic trends, periodic table
9.8
Title
Pauling's electronegativities of the elements
Caption
Electronegativity values vary from a low of 0.7 from Francium and Cesium to a high of 4.0 for Fluorine. Because noble-gas compounds are limited to just a few compounds of Kr and Xe, electronegativities for the Group 8A elements are not included.
Keywords
electronegativity, periodic table, bonding, electron affinity, periodic trends
9.9
Title
Electronegativities in relation to the periodic table
Caption
In general, electronegativities increase in the directions of the colored arrows. l
Keywords
periodic trends, electronegativity, periodic table
9.10
Title
Electronegativity & bond type
Caption
Bonding between atoms is a continuum from ionic to covalent. The larger the difference in electronegativity between two bonded elements, the more ionic in character that the bond becomes.
Keywords
bonding, ionic bonding, covalent bonding, polar covalent bonding.
9.11
Title
Nonpolar & polar covalent bonds
Caption
In the H2 molecule, there is an even distribution of electron charge density between the atoms. In the HCl molecule, electron charge density is displaced toward the Cl atom.
Keywords
polar covalent bonding, covalent bonding, bonding, electronegativity
9.11.1
Title
Designations in polar covalent bonds.
Caption
Greek letter delta (d) is used to indicate the polar nature of the bond.
Keywords
polar covalent bonding, paritally negative, partially positive, bonding,
9.11.2
Title
Diagram of a polar covalent bond
Caption
A cross-based arrow is used to indicate the polar nature of the bond.
Keywords
polar covalent bonding, paritally negative, partially positive, bonding,
9.11.4
Title
Structure of ethane
Caption
Hydrogenm atoms are terminal atoms in molecules.
Keywords
hydrogen, Lewis structure, bonding
9.11.5
Title
Lewis structure of COCl2
Caption
The central atom of a structure usually has the lowest electronegativity. In this case, the electronegativity of carbon is lowest of the elements in this molecule. Therefore, the other elements are drawn as bonded to the carbon.
Keywords
bonding, electronegativity, Lewis structures
9.11.6a
Title
Lewis structure of Chloric acid (HOClO2)
Caption
In oxoacids, hydrogen atoms are usually bonded to oxygen atoms.
Keywords
bonding, Lewis structures, oxoacids
9.11.6b
Title
Lewis structure of Sulfuric acid [(HO)2SO2]
Caption
In oxoacids, hydrogen atoms are usually bonded to oxygen atoms.
Keywords
obnding, lewis structures, oxoacids
9.11.7a
Title
Lewis structure of Sulfuryl fluoride (SO2F2)
Caption
Molecules and polyatomic acids usually have compact, symmetrical structures. Shown is SO2F2, which is has a symmetrical, spherical structure (left) not a linear one (right.)
Keywords
Lewis structures, bonding
9.12
Title
Concept of formal charge illustrated
Caption
Lewis structure (a) is more plausible than (b) because it has no formal charges vs. formal charges of +2, +2 and 0 for the atoms in the molecule.
Keywords
formal charge, lewis structures
9.12.13
Title
Central boron atom & 3 fluorine atoms
Caption
Boron in this Lewis structure does not have a complete octet. We most often see incomplete octets in Be, B, and Al.
Keywords
octet rule, lewis structures
9.12.14
Title
Possible Lewis structure for BF3
Caption
Boron-to-flourine double bond structure is one possible Lewis structure for BF3. It does ensure that each atom has a complete octet. However, the formal charges are not favorable. This is not an accurate representation of the structure of BF3.
Keywords
octet rule, Lewis structure
9.12.15
Title
Resonance structures of BF3
Caption
A hybrid of 4 resonance structures is the best Lewis representation of the "real" structure of a BF3 molecule.
Keywords
octet rule, resonance, lewis structures
9.12.16
Title
A coordinate covalent bond formed by a flouride ion
Caption
When both of the electrons in a bond are supplied by one of the atoms, a coordinate covalent bond is formed.
Keywords
lewis structure, bonding, coordinate covalent bond
9.12.17a
Title
Phosphorus pentachloride structure
Caption
Phosphorus violates the octet rule in this structure by having 5 bonds.
Keywords
octet rule, lewis structures, bonding, valence
9.12.17b
Title
Sulfur hexaflouride structure
Caption
Sulfur violates the octet rule in this structure by having 5 bonds.
Keywords
octet rule, lewis structures, bonding, valence
9.12.19
Title
Possible Lewis structure for perchlorate ion, pt. 1
Caption
In this Lewis structure for perchlorate ion, all atoms follow the octet rule but there is a positive formal charge on chlorine along with charges on each of the oxygen atoms. This suggests that this structure for perchlorate ion is not favorable.
Keywords
octet rule, Lewis structure, bonding, formal charge
9.12.20
Title
Possible Lewis structure for perchlorate ion, pt. 2
Caption
Although chlorine violates the octet rule in this Lewis structure, experimental evidence suggests that this structure possibly contributes to the hybrid structure.
Keywords
lewis structure, bonding, octet rule, formal charge
9.12.21A
Title
Possible Lewis structure for perchlorate ion, pt. 3
Caption
Experimental evidence suggests that this ionic structure possibly contributes to the hybrid structure of the perchlorate ion.
Keywords
bonding, lewis structure, resonance, hybrid structure, octet rule
9.13
Title
Some bond dissociation energies compared
Caption
The same quantity of energy (436 kJ/mol) is required to break all H2 bonds. In water, more energy is required to break the first H-O bond (499 kJ/mol) than to break the second (428 kJ/mol). The value of the H-O bond energy in Table 9.1 is an average value based on water and other compounds that contain the H-O bond.
Keywords
Bond energy, bond dissociation energy, enthalpy
9.14
Title
Caption
The values shown, in kilojoules per mole, are the amounts of energy absorbed in breaking bonds in the reactants, N2 and H2, and released in forming bonds in the product, N2H4.
Keywords
enthalpy, bond dissociation energy, bonding, enthalpy of formation
9.16.4Box
Title
Bromine molecules reacts w/unsaturated fats
Caption
The reddish brown color of bromine vapor (left) is removed when a strip of uncooked bacon is a placed in the beaker (right). Bromine molecules react with unsaturated fats in the bacon in a reaction similar to a hydrogenation reaction.
Keywords
hydrogenation, bonding, bromination, saturated fats, unsaturated fats.
9.16.5Box
Title
Corn oil and hydrogenation products
Caption
The unsaturated fats in oils, such as corn oil shown here, can be partially hudrogenated to form more saturated fats. Saturated fats are solids at room temperature. Corn oil margerine (a solid) is made from hydrogenated corn oil.
Keywords
saturated fats, unsaturated fats, bonding,
9.15
Title
Molecular model of ethene
Caption
Ethene, C2H4, contains 4 C-H bonds and a C=C double bond. The molecule is planar.
Keywords
spacefill model, bonding, alkene, double bond
9.16
Title
Molecular model of ethyne
Caption
Ethyne, C2H2, contains one C-C triple bond and 2 C-H bonds. The molecule is linear in structure.
Keywords
9.17
Title
The formation of polyethylene
Caption
In the synthesis of polyethylene, many monomer units join together to form giant polymer molecules. In this computer-generated representation, the yellow dots indicate a new bond forming as an ethylene molecule (upper right) is added to the growing polymer chain.
Keywords
polymer chemistry, polyethylene, addition reactions
9.17.1
Title
Production of plastic products
Caption
A giant bubble of a tough, transparent plastic film emerges from the die of an extruding machine. The film is used in packaging, consumer products, and food-service operations.
Keywords
polymer chemistry, plastic
9.17.2
Title
Amino acid polymerization
Caption
Two amino acid molecules join by eliminating a molecule of water between them and forming a peptide bond.
Keywords
amino acid, protein, polypeptide, bonding, polymerization, dehydration.
9.17.3
Title
Formation of a polypeptide
Caption
More amino acids can be added to the chain, until a long chain forms.
Keywords
amino acid, protein, polypeptide, bonding, polymerization

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