Housekeeping: Need to see progress on IA topics and thinking this week. If you need to speak to me, I'm available M-W between 10:35 - 1:00.
Agenda:
1. VSEPR Theory & Molecular Geometry.
Content Review:
Links: VSEPR Theory Molecular Geometry
Student Missions:
Mission 1: What Molecules Look Like.
Mission Objectives. You should be able to...
1. Explain VSEPR Theory.
2. Draw Lewis structures of covalent compounds using VSEPR Theory.
3. Use VSEPR Theory to predict molecular geometry of different compounds
4. Use VSEPR Theory to predict molecular polarity.
VSEPR stands for Valence Shell Electron Pair Repulsion. This theory helps us to predict the shape of molecules using their valence electrons. There are six steps to drawing Lewis structures using the VSEPR theory. Mr. Anderson walks you through the process. We will work some practice problems in class.
Agenda:
1. VSEPR Theory & Molecular Geometry.
Content Review:
Links: VSEPR Theory Molecular Geometry
Student Missions:
Mission 1: What Molecules Look Like.
Mission Objectives. You should be able to...
1. Explain VSEPR Theory.
2. Draw Lewis structures of covalent compounds using VSEPR Theory.
3. Use VSEPR Theory to predict molecular geometry of different compounds
4. Use VSEPR Theory to predict molecular polarity.
VSEPR stands for Valence Shell Electron Pair Repulsion. This theory helps us to predict the shape of molecules using their valence electrons. There are six steps to drawing Lewis structures using the VSEPR theory. Mr. Anderson walks you through the process. We will work some practice problems in class.
Mission 2: Keeping Things Straight.
Mission Objectives. You should be able to...
1. Identify and sketch the shapes and bond angles of different covalent compounds.
Remember that the book (and therefore the exams) will refer to shared pairs of electrons as electron domains. Here is what we know so far:
Molecules (or species) with two electron domains tend to be linear with bond angles of 180 degrees.
Species with three electron domains tend to be trigonal planar with bond angles of 120 degrees. But if one of the electron domains is a lone pair (or unshared pair [two dots]), it doesn't show in the overall shape. This results in species that are bent and have bond angles of 117 degrees.
Species with four electron domains tend to be tetrahedral and have bond angles of 109.5 degrees.
Pages 108-109 provide excellent summary tables of these shapes.
Mission Objectives. You should be able to...
1. Identify and sketch the shapes and bond angles of different covalent compounds.
Remember that the book (and therefore the exams) will refer to shared pairs of electrons as electron domains. Here is what we know so far:
Molecules (or species) with two electron domains tend to be linear with bond angles of 180 degrees.
Species with three electron domains tend to be trigonal planar with bond angles of 120 degrees. But if one of the electron domains is a lone pair (or unshared pair [two dots]), it doesn't show in the overall shape. This results in species that are bent and have bond angles of 117 degrees.
Species with four electron domains tend to be tetrahedral and have bond angles of 109.5 degrees.
Pages 108-109 provide excellent summary tables of these shapes.
Mission 3: Resonance.
Mission Objectives. You should be able to...
1. Draw and describe resonance structures of different compounds, such as benzene, carbonate, and ozone.
2. Explain the properties of giant covalent compounds in terms of their structures.
3. Define and explain coordinate covalent bonding.
Delocalization is when bonding electrons are not restricted to specific positions in molecules. They can spread out and give greater stability to thee molecule or ion. This happens frequently in molecules when there is more than one possible position for a double bond within a molecule. Example: Ozone. See below.
As a result, molecules like these demonstrate resonance. The Lewis structures are called resonance structures, as there are multiple versions of where the delocalized electrons can be. Look at the benzene example below. This is a specific example you are expected to know. You can look up carbonate on your own.
Resonance gives special properties to the structures where it occurs. It affects bond lengths and strengths, which influence reactivity. Acid and base strengths can be explained by resonance.
Play with this simulation.
Mission Objectives. You should be able to...
1. Draw and describe resonance structures of different compounds, such as benzene, carbonate, and ozone.
2. Explain the properties of giant covalent compounds in terms of their structures.
3. Define and explain coordinate covalent bonding.
Delocalization is when bonding electrons are not restricted to specific positions in molecules. They can spread out and give greater stability to thee molecule or ion. This happens frequently in molecules when there is more than one possible position for a double bond within a molecule. Example: Ozone. See below.
As a result, molecules like these demonstrate resonance. The Lewis structures are called resonance structures, as there are multiple versions of where the delocalized electrons can be. Look at the benzene example below. This is a specific example you are expected to know. You can look up carbonate on your own.
Resonance gives special properties to the structures where it occurs. It affects bond lengths and strengths, which influence reactivity. Acid and base strengths can be explained by resonance.
Play with this simulation.
Carbon has four allotropes: graphite, diamond, graphene and buckminsterfullerene. An allotrope is a structural modification of the same element. Each of the four examples contain nothing but carbon bonded in different ways. Graphite, diamond, and graphene are covalent network solids, in which the atoms are held together in a giant 3D lattice structure. Quartz is another example (SiO2). By contrast, buckminsterfullerene is molecular.
Read up on graphite, diamond, graphene, buckminsterfullerene and quartz. This is covered in pages 117-120. You're expected to know the properties of covalent network solids and details about each allotrope of carbon and silicon dioxide.
Coordinate covalent bonding. Typically, the shared pair of electrons originate from both atoms that form the bond; one atom contributes one electron to the shared pair and the second atom contributes the second electron. In coordinate covalent bonding, the shared pair of electrons comes from only one of the two atoms. Species that have coordinate covalent bonding: [NH4]+, [H3O]+, CO, Al2Cl6, and transition metal complexes. Look at the examples on pages 121-22.
Homework: Work on the related questions in your practice problem packet.
Read up on graphite, diamond, graphene, buckminsterfullerene and quartz. This is covered in pages 117-120. You're expected to know the properties of covalent network solids and details about each allotrope of carbon and silicon dioxide.
Coordinate covalent bonding. Typically, the shared pair of electrons originate from both atoms that form the bond; one atom contributes one electron to the shared pair and the second atom contributes the second electron. In coordinate covalent bonding, the shared pair of electrons comes from only one of the two atoms. Species that have coordinate covalent bonding: [NH4]+, [H3O]+, CO, Al2Cl6, and transition metal complexes. Look at the examples on pages 121-22.
Homework: Work on the related questions in your practice problem packet.