Originally created by Emily Adamson
Edited by M.Elizabeth, V. Sam
What’s the Kinetic Theory of Matter?
It’s a theory that helps explain difference between
the states of matter.
The Kinetic Theory of Matter states…
Matter is made up of constantly random moving
particles (also known as molecules or atoms).
KINETIC
THEORY
OF
MATTER
Assumptions/Postulates of KTM
1) All matter is made up of many very small particles (atoms/molecules) and particles
in gases are significantly smaller compared to the spaces between them.
Implies: There are some spaces between particles, hence, room for
movement/KE – all particles are moving; even solids (vibrating).
2) The particles are in constant straight-line motion.
Implies: Particles will continue moving in a straight line unless it bumps into
another particle/container
3) No kinetic energy is lost/gained overall during collisions between particles
Implies: Particles undergo Elastic Collisions – energy is transferred perfectly
hence, conservation of energy holds true.
4) There are NO forces of attraction and repulsion between the particles in a material
Implies: Particles do not attract to the containers; they do not influence other
particle movement unless they collide with them.
5) The particles at any given time have different speeds, however, the AVERAGE KE
of particles is proportional to the temperature of the substance.
Implies: Temperature is a reflection of the AVERAGE KE of the particles
3 STATES OF MATTER
SOLID
LIQUID
GAS
(Plasma)
SOLIDS
 Fixed shape and volume
 Normally hard and rigid
 Large force needed to change shape
 High density
 Incompressible
Model of Solids
 Closely packed together
 Occupy minimum space
 Regular pattern
 Vibrate about fixed
position
 Not free to move about
Under the Kinetic Theory of Matter…
Solids’ particles are so close
to each other that they
only vibrate in place.
LIQUIDS
Fixed volume but no fixed
shape
High density
Not compressible
Model of Liquids
 Occur in clusters with
molecules slightly
further apart as
compared to solids
 Free to move about
within confined vessel
Under the Kinetic Theory of Matter…
Liquids’ particles have
more space to move than
solids, but there is still an
attraction between them
and generally slide past
each other.
GASES
No fixed shape or volume
Low density
Compressible
Model of Gases
Very far apart
Travel at high speeds
Independent and random
motion
Negligible forces of
attraction between them
Under the Kinetic Theory of Matter…
Gases’ particles are far apart
and move around because
the attraction is so low it can
be disregarded. Movement is
rapid and random.
STATES OF MATTER
PLASMA
 A plasma is an
ionized gas.
 A plasma is a very
good conductor of
electricity and is
affected by
magnetic fields.
 Plasmas, like gases
have an indefinite
shape and an
indefinite volume.
Substances can change into different
States of matter and back.
WHY DOES THIS HAPPEN?
First, we need to know about…
ENERGY
“The ability to do work”
Energy causes things to happen around us.
It can be found in a number of different forms. It can be
chemical energy, electrical energy, heat (thermal energy),
light (radiant energy), mechanical energy, and nuclear
energy.
Units = Joules
Moving energy is KINETIC energy.
Stored energy is POTENTIAL energy.
There are multiple forms, such as:
• Stored chemical energy (PE)
• Stored elastic energy (PE)
• Stored gravitational energy (PE)
• Rotational energy (KE)
• Vibrational energy (KE)
• Translational energy (KE)
Energy in Substances
Internal energy is the total Kinetic
energy + Potential energy of all of a
substance’s atoms and molecules .
Internal Energy=
TRANSFER of Energy between
Substances
HEAT is the term used when we talk about
the transfer of thermal energy.
Transfer of HEAT is from:
HOTTER materials to COOLER materials
Temperature is the average amount of
kinetic energy in an object/substance.
But we usually measure it on a special
scale.
𝑲 = 𝒐𝑪 + 𝟐𝟕𝟑. 𝟏𝟓
K = Degrees Kelvin
Absolute Zero = 0 K
ZEROTH LAW OF
THERMODYNAMICS
 If A and C are in thermal equilibrium with B, then A is
in thermal equilibrium with C.
FIRST LAW OF
THERMODYNAMICS
+W if Work done
ON the system
Thermal
Energy
Temperature
Kinetic
Energy
• Increases as temperature increases
• Increases as kinetic energy increases
• Increases as kinetic energy increases
• Increases as thermal energy increases
• Motion increases as temperature increases
• Increases as thermal energy increases
Matter can change into different phases because of the
transfer of thermal energy between substances AND/OR
between a substance and the environment.
Forces that hold substances in one phase are overcome with the
addition of energy
SOLID
LIQUID
Tightly packed, in
a regular pattern
Vibrate, but do not
move from place
to place
Close together
with no regular
arrangement.
Vibrate, move
about, and slide
past each other
GAS
Well separated
with no regular
arrangement.
Vibrate and move
freely at high
speeds
PLASMA
Has no definite
volume or shape
and is composed
of electrical
charged particles
Overall, when temperature increases, atoms and
molecules’ motion increases (kinetic energy).
Thermal energy increases because the total amount of
kinetic energy increased due to the temperature
change.
THEY’RE ALL INTERTWINED!