AMORPHOUS and CRYSTALLINE SOLIDS.pptx

Amorphous and Crystalline

1. AMORPHOUS and CRYSTALLINE SOLIDS GRADE XII - OLC

2. LEARNING COMPETENCIES Describe the structure of crystalline and amorphous solid.

3. Crystalline Amorphous

4. WHAT ARE THE TWO GENERAL TYPES OF SOLIDS ? What features can be used to distinguish a crystalline solid from an amorphous solid? The differences in properties of these two groups of solids arise from the presence or absence of long range order of arrangements of the particles in the solid .

5. ARRANGEMENT of PARTICLES The components of a solid can be arranged in two general ways: CRYSTALLINE SOLID they can form a regular repeating three-dimensional structure called a crystal lattice , thus producing a crystalline solid’ AMORPHOUS SOLID they can aggregate with no particular long range order , and form an amorphous solid (from the Greek ámorphos , meaning “shapeless”).

6. Crystalline solids are arranged in fixed geometric patterns or lattices. Examples of crystalline solids are ice and sodium chloride (NaCl), copper sulfate (CuSO4), diamond, graphite, and sugar (C12H22O11). The ordered arrangement of their units maximizes the space they occupy and are essentially incompressible .

7. EXAMPLES

8. Crystalline Solids (vocabulary) Lattice is a three-dimensional system of points designating the positions of the components (atoms, ions, or molecules) that make up a crystal Unit cell is the smallest repeating unit of a lattice

9. COMMON UNIT CELLS and LATTICES

10. Amorphous solids have a random orientation of particles. Examples of amorphous solids are glass, plastic, coal, and rubber. They are considered super-cooled liquids where molecules are arranged in a random manner similar to the liquid state.

11. EXAMPLES

12. Differences between AMORPHOUS and CRYSTALLINE SOLIDS AMORPHOUS SOLIDS CRYSTALLINE SOLIDS a. Arrangement of Particles Particles are randomly arranged and have no ordered structure. Particles (atoms, molecules or ions) are closely packed and have an ordered three-dimensional structure. b. Melting Point Do not have sharp melting points; they melt over a wide range of temperatures Sharp melting points c. Examples Glass, rubber, and plastics Diamond, graphite, NaCl, CuSO 4 *5H 2 O, and sugar

13. FOR MORE INFORMATION… More than 90% of naturally occurring and artificially prepared solids are crystalline . Minerals, sand, clay, limestone, metals, alloys, carbon (diamond and graphite), salts (e.g. NaCl and MgSO4), all have crystalline structures.

14. They have structures formed by repeating three dimensional patterns of atoms, ions, or molecules. The repetition of structural units of the substance over long atomic distances is referred to as long-range order . Amorphous solids (e.g. glass), like liquids, do not have long range order, but may have a limited, localized order in their structures.

15. BEHAVIOR WHEN HEATED-CRYSTALLINE The presence or absence of long-range order in the structure of solids results in a difference in the behavior of the solid when heated. The structures of crystalline solids are built from repeating units called crystal lattices . The surroundings of particles in the structure are uniform, and the attractive forces experienced by the particles are of similar types and strength.

16. BEHAVIOR WHEN HEATED-AMORPHOUS Amorphous solids soften gradually when they are heated. They tend to melt over a wide range of temperature. This behavior is a result of the variation in the arrangement of particles in their structures, causing some parts of the solid to melt ahead of other parts.