* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Bonding
Molecular Hamiltonian wikipedia , lookup
Hydrogen bond wikipedia , lookup
Inductively coupled plasma mass spectrometry wikipedia , lookup
Livermorium wikipedia , lookup
Lewis acid catalysis wikipedia , lookup
Atomic nucleus wikipedia , lookup
Biochemistry wikipedia , lookup
Periodic table wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Low-energy electron diffraction wikipedia , lookup
Jahn–Teller effect wikipedia , lookup
History of chemistry wikipedia , lookup
History of molecular biology wikipedia , lookup
Halogen bond wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Atomic orbital wikipedia , lookup
X-ray photoelectron spectroscopy wikipedia , lookup
Metastable inner-shell molecular state wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Bond valence method wikipedia , lookup
Computational chemistry wikipedia , lookup
Molecular orbital wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Molecular dynamics wikipedia , lookup
Bent's rule wikipedia , lookup
Metallic bonding wikipedia , lookup
Extended periodic table wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Atomic theory wikipedia , lookup
Electron configuration wikipedia , lookup
Molecular orbital diagram wikipedia , lookup
History of molecular theory wikipedia , lookup
Electronegativity wikipedia , lookup
Resonance (chemistry) wikipedia , lookup
Bonding Chapter 8 Chemistry II Honors Types of Chemical Bonds Types of Bonds ✦ ✦ Ionic ✦ Electrons are transferred ✦ Metals react with nonmetals ✦ Ions paired have lower energy (greater stability) than separated ions Covalent ✦ Electrons are shared by nuclei ✦ Pure covalent (nonpolar covalent) - electrons are shared evenly ✦ Polar covalent - electrons shared unequally ✦ Atoms end up with fractional charges (ς+ and ς-) Electronegativity Electronegativity ✦ ✦ ✦ Electronegativity is the ability of an atom in a molecule to attract shared electrons to itself. Trends ✦ increases across a period ✦ decreases down a group (family) Greater electronegativity difference means less covalent and more ionic character. Electron Configuration and Physical Properties Electronegativity Electronegativity Electronegativity Sample Problem A ✦ In each case, which bond is more polar? ✦ B⎯Cl or C⎯Cl ✦ P⎯F or P⎯Cl Covalent Bond Energies and Chemical Reactions Bond Energies (Covalent) ΔH = ∑ ( bond enthalpies of bonds broken ) − ∑ ( bond enthalpies of bonds formed ) Table 8.4 (p.351) Covalent Bond Energies and Chemical Reactions Bond Energies (Covalent) Sample Problem B ✦ Estimate the ΔH for the following reaction C2 H 6 ( g ) + O2 ( g ) ⎯⎯ → 2CO2 ( g ) + 3H 2O ( g ) 7 2 Covalent Bond Energies and Chemical Reactions Bond Enthalpy and Bond Length ✦ As the number of bonds between two atoms increases, the bond grows shorter and stronger. Lewis Structures Drawing Lewis Structures 1.Add up the total number of valence electrons from all atoms. 2.Use a pair of electrons to form a bond between each pair of bonded atoms. 3.Arrange the remaining atoms to satisfy the duet rule for hydrogen and the octet rule for 2nd row elements. Lewis Structures Drawing Lewis Structures Sample Problem C ✦ Draw the following Lewis Structures ✦ PCl3 ✦ CH2Cl2 ✦ HCN ✦ NO+1 Daily Objectives Chemistry II Honors Today, I will be able to using VSEPR theory, describe the shape and properties of molecular compounds. determine the hybridization of molecular orbitals. • • LO 1.5, 1.9, 1.10, 1.13, 2.1, 2.17, 2.18, 2.21, 2.29, 2.30, 5.1 Lewis Structures AP Exam Sample Sample Problem D Answer the following questions using principles of chemical bonding and molecular structure. a.Consider the carbon dioxide molecule, CO2, and the carbonate ion, 2CO3 . i. Draw the complete Lewis electron-dot structures for each species. ii.Account for the fact that the carbon-oxygen bond length in 2CO3 is greater than the carbon-oxygen bond length in CO2. Lewis Structures AP Exam Sample Sample Problem D Answer the following questions using principles of chemical bonding and molecular structure. b.Consider the molecules CF4 and SF4. i. Draw the complete Lewis electron-dot structures for each molecule. ii.In terms of molecular geometry, account for the fact that the CF4 molecule is nonpolar, whereas the SF4 molecule is polar. Lewis Structures Resonance ✦ ✦ When more than one valid Lewis structure can be written for a particular molecule Actual structure is an average of the depicted resonance structures Lewis Structures Resonance Sample Problem E ✦ Draw the possible Lewis structures for the following: ✦ NO3-1 Molecular Structure: The VSEPR Model VSEPR ✦ ✦ ✦ Structure around a given atom is determined by minimizing electron-pair repulsion. Non-bonding and bonding electron pairs will be as far apart as possible Multiple bonds count as one effective electron pair Molecular Structure: The VSEPR Model Effect of Unshared Electron Pairs ✦ ✦ Lone pairs require more room than bonding pairs and tend to compress the angles between bonding pairs. Lone pairs do not cause distortion when bond angles are 120° or greater Molecular Structure: The VSEPR Model VSEPR Theory Sample Problem F ✦ Use VSEPR to predict the molecular geometry of the following: ✦ SF4 ✦ IF5 Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem G Answer the following questions about the element selenium, Se (atomic number 34). a.Samples of natural selenium contains six stable isotopes. In terms of atomic structure, explain wht these isotopes have in common, and how they differ. b.Write the complete electron configuration for a selenium atom in the ground state. Indicate the number of unpaired electrons in the ground-state atom, and explain your reasoning. Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem G Answer the following questions about the element selenium, Se (atomic number 34). c.In terms of atomic structure, explain why the first ionization energy of selenium is i. less than that of bromine (atomic number 35), and ii.greater than that of tellurium (atomic number 52). d.Selenium reacts with fluorine to form SeF4. Draw the complete Lewis electron dot structure for SeF4 and sketch the molecular structure. Indicate whether the molecule is polar or nonpolar, and justify your answer. Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem H First Ionization Energy Second Ionization Energy Third Ionization Energy (kJ/mol) (kJ/mol) (kJ/mol) Element 1 Element 2 Element 3 Element 4 1251 496 738 1000 2300 4560 1450 2250 3820 6910 7730 3360 The table above shows the first three ionization energies for atoms of four elements from the third period of the periodic table. The elements are numbered randomly. Use the information in the table to answer the following questions. Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem H First Ionization Energy Second Ionization Energy Third Ionization Energy (kJ/mol) (kJ/mol) (kJ/mol) Element 1 Element 2 Element 3 Element 4 1251 496 738 1000 2300 4560 1450 2250 a.Which element is most metallic in characteristic? reasoning. b.Identify element 3. Explain your reasoning. 3820 6910 7730 3360 Explain your Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem H First Ionization Energy Second Ionization Energy Third Ionization Energy (kJ/mol) (kJ/mol) (kJ/mol) Element 1 Element 2 Element 3 Element 4 1251 496 738 1000 2300 4560 1450 2250 3820 6910 7730 3360 c.Write the complete electron configuration for an atom of element 3. d.What is the expected oxidation state for the most common ion of element 2? Molecular Structure: The VSEPR Model AP Exam Practice Sample Problem H First Ionization Energy Second Ionization Energy Third Ionization Energy (kJ/mol) (kJ/mol) (kJ/mol) Element 1 Element 2 Element 3 Element 4 1251 496 738 1000 2300 4560 1450 2250 e.What is the chemical symbol for element 2? 3820 6910 7730 3360 f. A neutral atom of which of the four elements has the smallest radius? Covalent Bonding: Orbitals Hybridization ✦ ✦ The mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies Hybrid orbitals - equal energy produced by the combination of two or more orbitals on the same atom Covalent Bonding: Orbital Hybridization Sample Problem I ✦ Indicate the hybridization by the central atom in the following: ✦ NH2-1 ✦ SF4 Covalent Bonding: Orbital AP Exam Practice Sample Problem J GeCl4 SeCl4 ICl4 + ICl4 The species represented above all have the same number of chlorine atoms attached to the central atom. a.Draw the Lewis structure of each of the four species. Show all valence electrons in your structures. Covalent Bonding: Orbital AP Exam Practice Sample Problem J GeCl4 SeCl4 ICl4 + ICl4 The species represented above all have the same number of chlorine atoms attached to the central atom. b.On the basis of the Lewis structures drawn in part (a), answer the following questions about the particular species indicated. i. What is the Cl-Ge-Cl bond angle in GeCl4? ii.Is SeCl4 polar? Explain. iii.What is the hybridization of the I atom in ICl4 ? + iv.What is the geometric shape formed by the atoms in ICl4 ?