A. Description of the solid state according to the kinetic-molecular theory (KMT):

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Shawn Strickland
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2 A. Description of the solid state according to the kinetic-molecular theory (KMT): Have a definite shape and volume and a slow average kinetic energy Particles of a SOLID appear to vibrate around fixed points Solid particles are in a relatively fixed position but they do move in place (particles of a solid appear to vibrate around fixed points)

3 A. Description of the solid state according to the kinetic-molecular theory (KMT): Solid particles are closely packed together (more closely packed than liquid particles) Attractive forces (IM forces) between solid particles exert stronger effects in the solid state than in the liquid state.

4 A. Description of the solid state according to the kinetic-molecular theory (KMT):

5 B. Using KMT to Explaining the Following Properties of Solids: 1) Describe volume and shape of a solid. a) Solids have a definite volume and a definite shape. b) KMT: Definite volume- Solid particles are packed very close together c) KMT: Definite shape- Solid particles are in relatively fixed positions

2) Explain the relatively high density of

gases b) KMT: Solid particles are packed very

6 2) Explain the relatively high density of solids. a) Most solids are slightly denser than their corresponding liquid and much denser that gases b) KMT: Solid particles are packed very close together sodium in the solidstate: sodium in the liquidstate: sodium in the gas state:

7 B. Using KMT to Explaining the Following Properties of Solids: 3) Explain the relative incompressibility of solids. a) For practical purposes, solids can be considered incompressible b) KMT: Solid particles are packed very close together (there is practically no room to push them closer)

8 B. Using KMT to Explaining the Following Properties of Solids: 4) Explain the extremely low rate of diffusion between solids. a) KMT: Solid particles are in relatively fixed positions.

9 II. 2 Types of Solids: Crystalline Vs. Amorphous 1) Crystalline Solids = is a solid whose atoms, ions, or molecules are arranged in an orderly, geometric structure. Ex: Minerals, sand, clay, limestone, metals, carbon (diamond and graphite), salts (NaCl, KCl etc.)

10 CRYSTALLINE SOLIDS: Consist of single crystals or as groups of crystals fused together

11 Properties of Crystalline Solids: Defined melting points Ex: NaCl = 801 C; sucrose = 186 C Uniform crystal lattice Ex: A diamond is a perfect crystal lattice while the graphite arrangement is more random.

12 CrystallineSolids Crystal = a rigid body; a substance in which the particles are arranged in an orderly, geometric, repeating pattern. Unit Cell = simplest repeating unit of a crystal

14 CrystallineSolids Crystal Lattice = unit cells repeated over and over (block/brick) in a definite geometric arrangement Constructed of many unit cells packed solidly together

15 What Factors Affect Crystal 1) Temperature 2) Pressure Formation? Ex: carbon crystallizes as a diamond at HIGH pressure and crystallizes as graphite at LOW pressures

16 A. Types of CrystallineSolids a) Ionic Ionically bonded positive and negative ions in a regular pattern hard, brittle, high MP, good insulators Ex: NaCl

17 A. Types of CrystallineSolids b) Covalent Network Single atoms covalently bonded to nearest neighbors in an extensive pattern hard, brittle, high MP, usually non-conducting or semi-conducting Ex: Diamonds, graphite, quartz

crystal as a whole and are attracted to the positive ions Good

18 A. Types of CrystallineSolids c) Metallic Positive metal ions surrounded by negative valence electrons that belong to the crystal as a whole and are attracted to the positive ions Good conductors, varying MP, ductile, malleable Ex: All metallic elements

19 A. Types of CrystallineSolids d) Molecular Covalently bonded molecules attracted and held together by attractive forces (IM forces: LDF, dipole-dipole, hydrogen bonding) Low MP, relatively soft, easily vaporized, good insulators Ex: Sugar (sucrose), ice crystals, CO 2, I 2, NH 3

20 II. 2 Types of Solids: Crystalline Vs. Amorphous 2) Amorphous Solids = is a solid whose particles are not arranged in a regular, repeating pattern Ex: window glass, rubber, plastics, cement, many polymers No crystalline defects since no crystal structure Usually form when molten material cools quickly

21 Amorphous Solids Properties of Amorphous Solids: Particles are arranged randomly; without geometric shape No defined melting point

22 B. CRYSTAL DEFECTS: A perfect crystal is RARE! Most crystals contain defects! Defects = mistakes in the crystal

23 B. CRYSTAL DEFECTS: Dislocation = unit cells do not line up; particles are out of position

24 B. CRYSTAL DEFECTS: Inclusion = impurity in crystal Ex: Diamond inclusion

25 B. CRYSTAL DEFECTS: Doped = crystals are deliberately made impure Ex: Semiconductors (silicon, germanium) have impurities added to them to increase electrical conductivity Germanium crystal doped with indium.

26 C. Additional VOCAB: Sublimation = phase change from solid to gas Ex: Iodine crystals, dry ice Dry Ice Iodine Crystals

Solids SECTION Critical Thinking

Solids SECTION Critical Thinking SECTION 10.3 Solids A gas has neither a definite volume nor a definite shape. A liquid has a definite volume, but not a definite shape. A solid, the third state, has a definite volume and a definite shape.