Drexel-SDP GK-12 LESSON
Molecules and Mixtures
Subject 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
Summary
In 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 Connection
The 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 Knowledge
Atoms, matter, states of matter
Learning Objectives
After 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 / Motivation
Almost 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 / Definitions
Word
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
Chemical bond that forms by sharing electrons between two atoms.
Bond
Metallic
Chemical bond that forms between elements that have incompletely filled dBond
orbitals resulting in valence electrons that are not closely bound to the ion cores.
Chemical
Inter atomic forces that bind atoms together.
Bond
Cation
Positively charged atom, an atom that gave up an electron.
Anion
Negatively charged atom, an atom that took an electron
Hydrogen
A weak bond that forms though the attraction of the positive end one dipole to
Bond
the negative end of another dipole.
Atomic
Mathematical and physical constructs used to represent the arrangement of
Model
electrons in an atom.
Orbital
Spatial location of electrons around an atom
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Associated Activities
Use 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 Closure
Review the material briefly by asking the students questions.
Assessment
Pre-Lesson Assessment
Post-Introduction Assessment
Lesson Summary Assessment
Title: Molecules and Mixtures Assesmnet
Homework
Lesson Extension Activities
Additional Multimedia Support
YouTube is a great resource. Look up Dr. Quantum and the double slit experiment.
http://www.youtube.com/watch?v=DfPeprQ7oGc
References
Callister, William., Materials Science and Engineering: An Introduction. 6th Edition. Wiley, 2003
Attachments
Molecules and Mixtures.pdf
MoleculesandMixturesAssesment.pdf
Other
Redirect URL
Owner
Drexel University GK-12 Program
Contributors
Jennifer Atchison
Dorothea Holmes-Stanley
Copyright
Copyright 2008 Drexel University GK-12 Program. Reproduction permission is granted for nonprofit educational use.
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