Gasses, Liquids and Solids
● Kinetic molecular theory
○ Matter is composed of tiny particles (atoms, molecules, formula units)
○ The particles interact through both repulsive and attractive forces
○ As a gas, these tiny particles are in constant random motion with an
average kinetic energy dependent upon the temperature of the
surroundings
○ Collisions of these particles are elastic
PROPERTY SOLID LIQUID GAS
Volume and shape Definite volume and Definite volume and Indefinite volume
shape indefinite shape; and indefinite
takes the shape of shape; takes the
the container to the volume and shape
extent that it is filled of the container
Density high High, but usually low
lower than solid
Compressibility small Small, but usually large
greater than solid
Thermal expansion Very small; about Small; about 0.10% Moderate; about
0.01% per C* per C* 0.30% per C*
Phase changes
● Solid → melting→ liquid → vaporization → gas → deposition → solid
● Solid → sublimation → gas → condensation → liquid → freeing → solid
● Heat exchange
○ When a change (physical or chemical) occurs, it is usually accompanied
with an exchange of heat
○ A change that involves releasing heat to the surroundings its referred to as
an exothermic event
○ A change that involves absorbing heat from the surroundings is referred to
as an endothermic event
● “Hammer and nail” vs “separating a nail from a magnet” analogy
● Kinetic molecular theory
○ Matter is composed of tiny particles (atoms, molecules, formula units)
○ The particles interact through both repulsive and attractive forces
○ As a gas, these tiny particles are in constant random motion with an
average kinetic energy dependent upon the temperature of the
surroundings
○ Collisions of these particles are elastic
PROPERTY SOLID LIQUID GAS
Volume and shape Definite volume and Definite volume and Indefinite volume
shape indefinite shape; and indefinite
takes the shape of shape; takes the
the container to the volume and shape
extent that it is filled of the container
Density high High, but usually low
lower than solid
Compressibility small Small, but usually large
greater than solid
Thermal expansion Very small; about Small; about 0.10% Moderate; about
0.01% per C* per C* 0.30% per C*
Phase changes
● Solid → melting→ liquid → vaporization → gas → deposition → solid
● Solid → sublimation → gas → condensation → liquid → freeing → solid
● Heat exchange
○ When a change (physical or chemical) occurs, it is usually accompanied
with an exchange of heat
○ A change that involves releasing heat to the surroundings its referred to as
an exothermic event
○ A change that involves absorbing heat from the surroundings is referred to
as an endothermic event
● “Hammer and nail” vs “separating a nail from a magnet” analogy
