Unit A: Mix and Flow of Matter
Section 2.4 The Particle Model of Matter
The Particle Model of Matter
The Particle Model of Matter attempts to explain how the individual molecules and atoms of
matter react and behave in everyday situations.
There are four basic points to this theory:
1. All matter is made up of tiny
particles, and different substances
are made up of different particles
2. The tiny particles of matter are always moving and vibrating; they are almost never at
rest
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In Solids, particles are wriggling in one place
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In liquids, particles are sliding around and over each other
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In gases, particles are moving as far as the space will let them
3. Particles of matter may be attracted or bonded to one another
4.
Particles have spaces between them, which may vary in size
How The Particle Model Explains Mixing Substances
Particles are different sizes and when two substances are mixed, the smaller particles fill the
spaces between the larger particles. The particle model also states that particles are attracted
to each other. However, in some substances particles can be attracted more to particles in
other substances than to its own particles making it more soluble (dissolving faster).
Factors Affecting The Rate Of Dissolving
The speed at which the solute dissolves in a solvent is called the rate of dissolving and can be
affected by:
1. Temperature - Increasing the temperature = more particle movement
2. Size of the pieces - small solute pieces dissolve faster than bigger pieces because there is
more surface area
3. Stirring - stirring moves all particles around, creating more bumping of particles
Section 2.4 Check and Reflect Questions
1. List the four main points that outline the particle model of matter.
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2. Use the particle model of matter to complete the statements below.
(a) Solids have a definite shape because…
(b) Fluids (liquids and gases) flow because…
(c) Gases do not have a definite shape because…
3. The particle model of matter can be summarized with only a few short words describing
each point, such as:
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Particles
Movement
Spaces
Attractions / bonding
Using the simple summary above, create your own acronym to help you to remember
the particle model of matter. An acronym uses the first letter of each point to create a
sentence an easy-to-remember saying (such as Very Excited Mother Just Served Us
Nachos to represent the order of the planets). Use the space below to create your own
acronym for the particle model.
4. Name three ways that you can speed up the dissolving rate. Explain each method using
the points from the particle model of matter (the behavior of the molecules)
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5. In the demonstration, why did the potassium permanganate crystals start to dissolve in
water without being stirred? Use the particle model of matter to help explain this
phenomenon.
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