Honors Chemistry
08-04 – The Nature of Solids
Expanding the Kinetic Theory
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Objectives

When you complete this presentation, you will be able to …
o use kinetic theory to explain the properties of solids including

melting point

freezing point
o explain the significance of the crystal structure in solids
o define the unit cell of a particular crystalline structure
o define and give examples of solid allotropes
Introduction

Solids are more like liquids than gases.
o Solids are ____________ like liquids.
o Solids have a definite ____________.

However, solids also have a definite ____________, which is not like either
liquids or gases.

We will continue to use the kinetic theory to explain the behavior of solids.
Assumptions

The particles in a solid are ____________ ____________ ____________ attracted to
other particles than are particles in liquids or gases.
o This means that the individual solid particles …

are so attracted to the other particles that it is very ____________
for them to move very far.

The particles in a solid are arranged in an orderly fashion in ____________
____________.
o This means that the individual solid particles …

are ____________ ____________ ____________ to form the solid

are packed so tight together that the solid is ____________.
Honors Chemistry

08-04 – The Nature of Solids
Expanding the Kinetic Theory
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The particles in a solid are in ____________ and ____________ motion.
o This means that the individual solid particles …

vibrate ____________ in place in the solid

vibrate faster at ____________ temperatures and slower at
____________ temperatures
Melting Point

When the temperature of a solid ____________, the particles in the solid move
faster and faster in place.

At one temperature, the ____________ ____________, the solid particles start to
move fast enough to become liquid particles.

Likewise, as the temperature in a liquid falls to that same particular
temperature, the ____________ ____________, the liquid particles move slow
enough to become solid particles.

For any particular compound, the melting point and the freezing point are
____________ ____________ ____________.

We can have both solid and liquid at the temperature in ____________ with
individual particles moving from ____________ to ____________ and back again.
freezing
Solid  Liquid
melting
Crystal Structures

In a crystal, the particles are arranged in an orderly, repeating, ____________
pattern.

The ____________ of the crystal reflects the ____________ of the particles within the
solid.
Honors Chemistry

08-04 – The Nature of Solids
Expanding the Kinetic Theory
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There are ____________ crystal groups.
cubic
hexagonal
Fluorite
tetragonal
rhombohedral
Rutile
Corundum
orthorhombic
monoclinic
Barite
Cerussite
triclinic
Rhodonite
Boron
Unit Cell

The shape of a crystal depends on the arrangement of the particles within it.

The ____________ group of particles within a crystal that retains the ____________
____________ of the crystal is the ____________ ____________.
o A cubic structure has 3 different possible unit cells.
a) Simple cubic
b) Face centered cubic (fcc)
c) Body centered cubic (bcc)

Each of the crystal groups has a number of different kinds of unit cells.
o The cubic group can have three different kinds of unit cells.
o The tetragonal group can have two different kinds of cells.
o The monoclinic group can also have two different kinds of cells.
Honors Chemistry
08-04 – The Nature of Solids
Expanding the Kinetic Theory
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o The orthorhombic group can have four different kinds of cells.
o The rhombohedral, hexagonal, and triclinic groups have only one
kind of cell each.
Allotropes

____________ are two or more ____________ molecular forms of the ____________
element in the same physical state
o For example, carbon.
Honors Chemistry
08-04 – The Nature of Solids
Expanding the Kinetic Theory
o For example, phosphorus.
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