9th Grade Physical Science
Unit 2. Get a Charge Out of Matter
Activity #2A: Classifying Matter by Its Composition
#2A
To Begin
In activity #1 you thought about what might be different between salt water and pure water. You reasoned what
it means to dissolve sugar into water. In this activity, you will begin to classify particles of matter (such as salt,
water and sugar) based on their sub-microscopic composition.
First, please complete the reading, A Short History of Chemistry. As you read, highlight key passages and make
notes as part of your individual reading strategies. Then you will come together as a group to agree on the
central idea of the text and use key details to support your choice.
Learning Goals for this activity
Students will …
• determine the central idea of a text and support it with key details
• use of model to to compare and contrast the terms: element, compound, molecule, atom, pure substance,
mixture, homogeneous and heterogeneous.
Process & Procedure
1. a. As a team, identify the central idea of the text, A Short History of Chemistry, as it relates to matter and to
human technology. Identify 5-7 key details that support the central idea of that reading. Each oval should
contain a descriptive phrase about a one key detail.
Central idea:
b. Add one of your team’s key details to the active board at the front of the room . Be sure that the
your choice of detail has not already been used.
2. You will work with a partner to build models of different types of molecular particles. Molecular
particles show the sub-microscopic structure of the particle…shows the # and type of atoms that
make up the molecular particle.
3. Discuss each term and its definition, listed below, with your partner. Build a model of a molecular
particle that matches each definition. Sketch your model and write a note that explains the
structure of that molecular particle. Use shading or colored pencils to sketch the different atoms
involved. Be sure to show your models to your teacher before you put them back.
Single Particles
Type of
Matter
Atom
Molecule
Element
Definition
Sketch with Annotation (description)
The smallest particle of an element.
Can combine with other atoms.
choose an atom found in water
The smallest particle of a pure
substance that still possesses the
properties of the substance (could be
an element or a compound)
choose a molecule of water
A pure substance made of only one
type of atom.
choose a valuable element
Multiple Particles
Compound A pure substance that is composed of
molecules made of more than one
kind of element (atom).
your choice: make three particles of it
Pure
A sample of matter that consists of
Substance only one kind of matter (could be
compound or element)
your choice: make several particles;
identify your pure substance as an element
or compound
Mixture
A sample of matter consisting of two
or more pure substances. The pure
substances in a mixture could be
physically separated from each other.
homogenous
heterogenous
•Homogenous- evenly mixed
throughout
•Heterogenous- unevenly mixed
Stop and Think
1. The prefix di means two. A diatomic molecule is a molecule made of two atoms (either same atoms or
different atoms. Describe and sketch a particle model that would represent a diatomic element (same
atoms) and a diatomic compound (different atoms).
Diatomic element
Diatomic compound
2. Describe an actual example found in your daily life of a pure substance, a homogenous mixture and a
heterogeneous mixture.