Do Now: What are the three types of bonds? Compare them. Which compounds contain which bonds? Why?

Metallic Bond Properties of metals? High electrical and thermal conductivity, luster (shiny), malleable, ductile Valence electrons are delocalized. The bond results from the electrostatic attraction between the delocalized electrons and the metallic ions. Positive ions (cations) in a "sea" of delocalized electrons.

Ionic Bond Transfer of electrons Metals lose elelctron(s) to form positive ions (cations) Nonmetals gain electron(s) to form negative ions (anions) Li. :Cl: :. Li + :Cl: :.. - Lower IE More negative EA

Ionic Compounds Properties??? Brittle, crystalline substances with high melting points, most soluble in water, conduct electricity when melted and in solution,

Lattice Energy

Molecular Compounds - Covalent Bonding Gas, Liquid,Solid with generally low melting points, brittle, do not conduct electricity Looking at hydrogen molecule, H 2 High electron density between nuclei. The atoms are held together because the two positive nuclei are attracted to the concentration of negative charge between them. The shared pair in a covalent bond acts as “glue”

Lewis Structures Use Lewis Dot Diagrams Lone pairs (nonbonding pairs – unshared) Bonding Pairs –shared between two nuclei

Draw Lewis structures for N 2, O 2, and F 2 Compare bond length and bond enthalpy, enthalpy change  H to break bond Estimate  H for synthesis of ammonia

Energy Calculations Estimate  H f o for potassium chloride provided with: Lattice energy of KCl: -690 kJ/mol First IE for K: 419 kJ/mol Electron affinity of Cl: -349 kJ/mol Bond Energy of Cl 2: 239 kJ/mol Enthalpy of sublimation for K: 64 kJ/mol

Ionic and Covalent Bond are on the extremes, what about HCl Polar covalent bond Dipole moment – measure of is the measure of net molecular polarity, tell us about the charge separation in a molecule.

Electronegativity – ability of atom to attract electrons. Explain trend H and O S and S Li and Cl - What type of bond exists between…

Lewis Structures Type of structural formula that uses dots or dashes to indicate bonds Bromine molecule, Br 2 Water, H 2 O Ethyne, C 2 H 2 Methane, CH 4

DO NOW Draw the Lewis Structure for NCl 3 and HCN Indicate the shared and unshared pairs of electrons What is another term for shared electrons?

alence hell lectron air epulsion VSEPRVSEPR This theory states that pairs of valence electrons are arranged as far apart from each other as possible

Draw Lewis Structures for H 2, C 2 H 2, BH 3, NH 3, H 2 O, PCl 5, SF 6 In the last two examples, will you satisfy the octet rule? Explain

ExampleShapeAngle H 2 and C 2 H 2 Linear180º BH 3 Trigonal Planar120º MethaneTetrahedral ~109.5º AmmoniaTrigonal Pyramidal~107º WaterBent (V-shaped)~104.5º Phosphorus Pentachloride Trigonal Bipyramidal 90º, 120º Sulfur hexafluoride Octaheral90º ?

A molecule’s attractive forces impacts its melting and boiling points as well as many other properties. Will a molecule that is highly attracted to another molecule of its kind have a high boiling point or a low boiling point? In which state will the substance typically be found at room tempterature?

Polarity of Molecule Polar Molecule (Dipoles) – have a positive end and a negative end Nonpolar Molecule - has an equal distribution of electrons and therefore no positive or negative ends First let’s review: Distinguish between polar and nonpolar bonds. What do those terms mean and how do you make this determination?

Polar or Nonpolar Molecules… H 2 CO 2 H 2 O Shape of molecule and polarity of bonds determines polarity of molecule.

Valence Bond Theory Covalent bonds form when a pair of electrons is shared by overlapping atomic orbitals on adjacent atoms. Consider HF, draw the valence electron configuration for H and F 2p __ __ __ H 1s__ F 2s__ X X

Methane, CH 4 Draw the valence electron configuration for C and H Carbon’s four sp 3 hybrid orbitals Add four hydrogen s orbitals

Boron Trihydride, BH 3 Draw the valence electron configuration for B Boron’s three sp 2 hybrid orbitals, has 1 empty p orbital Add three hydrogen s orbitals

Ethyne, C 2 H 2 Draw the valence electron configuration for C Add two hydrogen s orbitals Each carbon has two sp orbitals and two p orbitals

Sigma (  ) bond – results from end to end overlap of atomic orbitals Pi (  )bond – side be side overlap of atomic orbitals Which bonds are  Try C 2 H 4

Summary of Valence Bond Theory HybridizationVSEPR theory shapeExample spLinear (2)C2H2C2H2 sp 2 Trigonal planar ( 3)BH 3 sp 3 Tetrahedral, bent (2 shared, 2 unshared), pyramidal (4) CH 4 Trigonal bipyramidal (5)PCl 5 Octahedral (6)SF 6 sp 3 d sp 3 d 2