Chemical Bonding Molecular Geometry

Ch. 6 Sections 1-4 Review In general, what determines whether atoms will form chemical bonds? Atoms will form a chemical bond if their potential energy is lowered in doing so. Describe the difference between ionic and covalent bonding. Ionic bonds form as a result of the transfer of electrons between two atoms with a large difference in electronegativity. Covalent bonds form when electrons are shared between two atoms of similar or slightly different electronegativity.

Ch. 6 Sections 1-4 Review What types of bonds form between the following pairs of atoms: Ca-Cl, O-H, O-O? Ionic, polar covalent, nonpolar covalent What is the meaning of the word polar, as applied to chemical bonding? Polar refers to bonds that have an uneven distribution of charge. What type of bonding exists (ionic or covalent) in the compounds: NaCl, H2O, CH4? Ionic, covalent, covalent

Ch. 6 Sections 1-4 Review List 3 properties of ionic compounds. Hardness, brittleness, electrical conductivity in molten state, high melting and boiling points. What accounts for the properties of ionic compounds listed above? Cations and anions are arranged in a crystal lattice. Draw the Lewis dot diagram for C3H6.

Ch. 6 Sections 1-4 Review How are single, double, and triple covalent bonds different? One, two, and three pairs of electrons are shared; bond energy increases with the number of bonds and bond length decreases with the number of bonds. Draw the Lewis dot structure for SO2. Show both resonance structures.

Ch. 6 Sections 1-4 Review What properties of metals contribute to their tendency to form metallic bonds? Most metals have unfilled outermost orbitals, low ionization energies, and low electronegativities. What are some common properties of metals? Electrical and thermal conductivity, luster, malleability, ductility, high melting and boiling points

Hybridization Hybridization – mixing of atomic orbitals of similar energy to produce new orbitals of equal energy

Hybridization

Intermolecular Forces Covalent, ionic, and metallic bonds can be considered to be intra-molecular forces Intermolecular Forces- forces of attraction between molecules; weaker than covalent, ionic, and metallic bonds.

Boiling Points and Bonding Types Substance B.P. (1 atm) in oC Nonpolar covalent H2 -253 O2 -183 Cl2 -34 Br2 59 CH4 -164 CCl4 77 C6H6 80 Polar Covalent PH3 -88 NH3 -33 H2S -61 H2O 100 HF 20 HCl -85 ICl 97

Boiling Points and Bonding Types Substance B.P. (1 atm) in oC Ionic NaCl 1413 MgF2 2239 Metallic Cu 2567 Fe 2750 W 5660

Molecular Polarity Molecular polarity depends on the polarity of the bonds that make up a compound and the molecular shape. A dipole moment results when a polar molecule has a center for positive charge separate from a center for negative charge