Drexel-SDP GK-12 LESSON

Molecules and MixturesSubject Area(s) Chemistry, Physics and Engineering

Associated Unit Geology

Lesson Title Molecules and Mixtures

Fluorescence micrograph of crystallized Alexa Fluor 555 dye. (Organic fluorescent compound) (www.invitrogen.com)

Grade Level __ (__8-_11_)

Lesson # _1_

Lesson Dependency none

Time Required 150 mins

SummaryIn this lesson, students will be introduced to mixtures, compounds and types of bonding. Although the lesson was originally taught to an 8th grade class, a brief introduction to quantum mechanics is included because the shape of the molecular orbitals provide a more concrete model to understand how bonding occurs.

Engineering ConnectionThe foundation of materials engineering is based on the understanding of the relationship between the physical and chemical properties of a material, their underlying structure and the processing that produces the structures. Understanding the role of electrons in the bonding process has been crucial to the advances in the 20th century in electronics, metallurgy, and plastics.

Keywords: Molecules, mixtures, compounds, covalent bonding, ionic bonding, bonding energy, moleualr orbitals

Educational Standards Science: 3.1.7 B, 3.1.7 C, 3.4.7 A Math: 2.7.8D, 2.9.8 H, 2.11.8 A

Pre-Requisite KnowledgeAtoms, matter, states of matter

Learning ObjectivesAfter this lesson, students should be able to: Describe the difference between a molecule, a mixture, and a compound

Estimate physical properties such as thermal coefficient of expansion, and relative bond strength, and elastic behavior of a solid based on the shape of the bond energy well

Describe covalent, and ionic and metallic bonding and give examples of compounds that form from each type of bonding

Qualitatively describe the role of electrons in bonding

Describe the difference between a molecule and a crystal

Sketch the energy well formed by a bond

Explain Bohr’s Model of the atom

Build a model of the electron orbitals in an atom base on the wave mechanical model

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Introduction / MotivationAlmost everyone has a TV, phone, uses plastic bottles, has access to a car, etc. The everyday use of technology is common place and the engineered materials that go in to the artifacts we use and trust are a result of the revolution instigated by quantum mechanics the resultant insight of how electrons behave in solids. This lesson was taught as a part of the geology curriculum so particular emphasis is given to metal and ceramic crystals.

Lesson Background & Concepts for Teachers

Look over the power point presentation and review any basic chemistry text for the background information for this lesson.The concepts for this lesson:

The electron cloud around the atom participates in bonding The type of bonding in a material depends on the relative position the element has

on the period table Physical and chemical properties of a compound is determined by the type of

bonding Shape of the orbitals explains how some compounds are formed and dictates

molecular shape

Vocabulary / DefinitionsWord Definition

Mixture Two or more substances physically mixed with no chemical bond. Compound Two or more elements bonded together in fixed proportion that results in a

substance that has different chemical and physical properties.Ion An atom or molecule with a net electric charge due to the loss or gain of one or

more electrons.Molecule A group of atoms bonded together, representing the smallest fundamental unit of

a chemical compound that can take part in a chemical reaction. Crystal Ions positioned in a repetitive three-dimensional pattern.Ionic Bond Chemical bond that forms when one atom gives and electron to another atom.Covalent Bond

Chemical bond that forms by sharing electrons between two atoms.

Metallic Bond

Chemical bond that forms between elements that have incompletely filled d-orbitals resulting in valence electrons that are not closely bound to the ion cores.

Chemical Bond

Inter atomic forces that bind atoms together.

Cation Positively charged atom, an atom that gave up an electron.Anion Negatively charged atom, an atom that took an electronHydrogen Bond

A weak bond that forms though the attraction of the positive end one dipole to the negative end of another dipole.

Atomic Model

Mathematical and physical constructs used to represent the arrangement of electrons in an atom.

Orbital Spatial location of electrons around an atom

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Associated ActivitiesUse colored clay to build models of the orbitals. I projected the graphs on the in the power point on a screen as a guide. Ask the students to build two atoms and experiment with how these atoms could form bonds.

Ask the students to stand up and make groups. In the groups, ask them to pass a ball, or share a ball to demonstrate ionic and covalent bonding. As class arrange the students in a lattice to build a crystal. (Boys can be cations and girls anions). I also have a ball and stick model of NaCl (rock salt)Also see “Elements Poster” activity

Lesson ClosureReview the material briefly by asking the students questions.

AssessmentPre-Lesson AssessmentPost-Introduction AssessmentLesson Summary AssessmentTitle: Molecules and Mixtures AssesmnetHomework

Lesson Extension Activities

Additional Multimedia SupportYouTube is a great resource. Look up Dr. Quantum and the double slit experiment. http://www.youtube.com/watch?v=DfPeprQ7oGc

ReferencesCallister, William., Materials Science and Engineering: An Introduction. 6th Edition. Wiley, 2003

AttachmentsMolecules and Mixtures.pdfMoleculesandMixturesAssesment.pdf

OtherRedirect URLOwnerDrexel University GK-12 Program

ContributorsJennifer AtchisonDorothea Holmes-Stanley

CopyrightCopyright 2008 Drexel University GK-12 Program. Reproduction permission is granted for non-profit educational use.

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