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Lesson Plan Chemistry 9th Grade Date Teacher’s Name Lesson Plan Type Grade Level Subject/Topic Timeline
: April 13, 2016 : Ibrahim Ozkaya : Direct instruction :9 : Chemical Bonding : 15 minutes
TEKS objectives: Covalent Bonding and Molecular Compounds Understand Formation of a Covalent Bond and Characteristics of the Covalent Bond
Objectives and Goals 1. Define molecule and covalent bonding. 2. Explain the relationships between potential energy, distance between approaching atoms, bond length, and bond energy. 3. State the octet rule. Key Vocabulary: Covalent bonds, covalent compounds, single bond, double bonds, triple bonds, octet, octet rule, valence, valence electrons, polar, nonpolar covalent, polar covalent bond Materials needed for this class: Computer, Projector, power point presentation of the subject, board, and marker, Molecules set(1 set for each group), Visual Aids Set induction: 3 min Students watch video about: How different atoms held together? “Why do elements combine to form compounds?”; “How do elements combine?” and “Why do they stay combined?”
Teaching by direct instruction (PowerPoint presentation ) 10 min Covalent bonding and molecular compounds -Molecular compounds Molecule .Neutral group of atoms that are held together by covalent bonds .Compose most living things
-Molecular compound– Chemical compound whose simplest units are molecules
Chemical formula – Indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts H2O CO2 C12H22O11
Molecular formula – Shows the types and numbers of atoms combined in a single molecule of a molecular compound H2O CO2 C12H22O11
Diatomic molecule – Molecule containing only two atoms H2 O2 N2
Formation of a Covalent Bond Nature favors bonding because Puts atoms at lower potential energy Approaching nuclei and electrons Attracted to each Decrease in potential energy
At the same time, both nuclei and two electrons repel each other Increase in potential energy
Potential energy is minimized when attractive forces are equal to the repulsive forces
: Bond Length and Stability. Bonds are most stable When the potential energy of the bonded atoms is minimized.
Chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest occupied energy level.
Hydrogen is an exception because it is stable with 2 electron in outer shell.
The eight electrons come from the main-group energy levels being filled. s2p6 totals 8 electrons
Multiple Covalent Bonds
Double bond – Covalent bond produced by the sharing of two pairs of electrons between two atoms
Triple bond – Covalent bond produced by the sharing of three pairs of electrons between two atoms
(Checking for understanding-Monitored Independent Work) :
Modifications/Accommodations: student in need.
Simplify and enlarge the sentences of worksheet for the
Example: Draw the Lewis Structure for methanal, CH2O, which is also known as formaldehyde. 1. Determine the type and number of atoms in the molecule 1C 2H 1O 2. Write the electron-dot notation for each type of atom in the molecule C H O 3. Determine the total number of valence electrons in the atoms to be combined 1 x 4e- = 4e2 x 1e- = 2e1 x 6e- = 6e12e-
C H O
4. Arrange the atoms to form a skeleton structure for the molecule. If Carbon is present, it is the central atom. Otherwise, the least-electronegative atom is central (except for hydrogen, which is never central). Then connect the atoms by electron-pair bonds. 5. Count the electrons in the structure to be sure that the number of valence electrons used equals the number available. Be sure the central atom and other atoms besides hydrogen have an octet.
Quiz. 3 question for evaluation whether topic comprehended
1. Determine the number of atoms of each element present in the molecule. The formula shows one carbon atom, two hydrogen atoms, and one oxygen atom.
2. Write the electron-dot notation for each type of atom. Carbon is from Group 14 and has four valence electrons. Oxygen, which is in Group 16, has six valence electrons. Hydrogen has only one electron.
3. Arrange the atoms to form a skeleton structure for the molecule, and connect the atoms by electron-pair bonds.
Closure: Wrap up questions. 2 min
1. Draw the Lewis structure for carbon dioxide, CO2. 2. Draw the Lewis structure for hydrogen cyanide, which contains one hydrogen atom, one carbon atom, and one nitrogen atom.
Homework: work sheet
Worksheet 1. Use the concept of potential energy to describe how a covalent bond forms between two atoms.
2. Name four elements that form compounds that can be exceptions to the octet rule. 3. Explain why resonance structures are used instead of Lewis structures to correctly model certain molecules.
4. Bond energy is related to bond length. Use the data in the tables below to arrange the bonds listed in order of increasing bond length, from shortest bond to longest. Bond H—F H—I H—Cl H—Br C—C
Bond Energy (kJ/mol) 569 299 432 366 346
Draw the Lewis Structures for the following: Formula 5. SF2