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Explore the nature of solids, crystal structures, and allotropes, such as buckyball carbon. Learn about unit cells, crystal systems, and the unique properties of non-crystalline solids. Test your knowledge with the section quiz.
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13.3 The Nature of Solids • In 1985, scientists discovered a new form of carbon. They called this form of carbon buckminsterfullerene, or buckyball for short. You will learn how the arrangement of particles in solids determines some general properties of solids.
13.3 A Model for Solids • A Model for Solids • How are the structure and properties of solids related?
13.3 A Model for Solids • The general properties of solids reflect the orderly arrangement of their particles and the fixed locations of their particles.
13.3 A Model for Solids • The melting point (mp) is the temperature at which a solid changes into a liquid.
13.3 Crystal Structure and Unit Cells • Crystal Structure and Unit Cells • What determines the shape of a crystal?
13.3 Crystal Structure and Unit Cells • In a crystal, the particles are arranged in an orderly, repeating, three-dimensional pattern called a crystal lattice.
13.3 Crystal Structure and Unit Cells • The shape of a crystal reflects the arrangement of the particles within the solid.
13.3 Crystal Structure and Unit Cells • Crystal Systems • A crystal has sides, or faces. Crystals are classified into seven crystal systems.
13.3 Crystal Structure and Unit Cells • These minerals show four out of the seven crystal systems.
13.3 Crystal Structure and Unit Cells • Three kinds of unit cells can make up a cubic crystal system.
13.3 Crystal Structure and Unit Cells • The smallest group of particles within a crystal that retains the geometric shape of the crystal is known as a unit cell. • A crystal lattice is a repeating array of any one of fourteen kinds of unit cells. • There are from one to four types of unit cells that can be associated with each crystal system.
13.3 Crystal Structure and Unit Cells • Allotropes • Allotropes are two or more different molecular forms of the same element in the same physical state. • Allotropes have different properties because their structures are different. • Only a few elements have allotropes.
13.3 Crystal Structure and Unit Cells • Carbon Allotropes
13.3 Crystal Structure and Unit Cells • Non-Crystalline Solids • An amorphous solid lacks an ordered internal structure. • Rubber, plastic, asphalt, and glass are amorphous solids. • A glass is a transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing.
13.3 Section Quiz. • 13.3
13.3 Section Quiz • 1. A solid will melt when • all the particles have the same kinetic energy. • bonds form between the particles. • disruptive vibrations overcome attractive forces. • attractions overcome disruptive vibrations.
13.3 Section Quiz • 2. Which of the following affect the shape of crystals? • (1) angles between the faces • (2) number of edges of equal length per face • (3) size of the crystal • (1) only • (2) only • (3) only • (1) and (2)
13.3 Section Quiz • 3. Allotropes have different properties because • their atoms are arranged in different patterns. • they are composed of different elements. • they are in different states. • they consist of different isotopes of the same element.
