Properties of Solids by pengtt


									Properties of Solids
I. The Solid State: Types of Solids
   A. Crystalline Solids
       1. have a regular arrangement of their
       2. Types
           a. Ionic solids
           b. Molecular solids
           c. Atomic solids
2. Types
   A.) Ionic solids: contains cations & anions.
       Ex. Sodium chloride
   B. Molecular solids: made of covalently
    bonded molecules
       Ex. Ice
   C. Atomic solids: made up of atoms
       Ex. Carbon (diamond)
   B. Properties of solids
       Can vary dramatically, differences are due to differences in
           Ex. with atomic solids
           Argon –
                 low melting point = -189°C
                insulator
           Diamond –
                 high melting point = 3500°C
                Insulator
                Hardest natural substance
           Copper –
                 high melting point = 1083°C
                Very conductive
                soft
Solid Argon
II. Bonding in Solids
   A. Ionic solids
       1. Stable
       2. High melting points
       3. Held together by STRONG FORCES b/w
        oppositely charged ions
       4. Structure – ions are packed as closely together
        as possible
II. Bonding in Solids
   B. Molecular solids
       Melt at low temperatures b/c intermolecular
        forces are weak between the molecules
Carbon dioxide crystal
II. Bonding in Solids
   C. Atomic Solids
       Properties vary greatly b/c of the different ways
        in which the atoms can interact with each other.
       Ex. Group 8 elements have low melting points b/c
        they have 8 valence electrons and cannot form
        covalent bonds with each other, so they are held
        together by weak Londin dispersion forces.
       Ex. Diamond, a form of carbon, is one of the
        hardest know substances, which comes from its
        very strong covalent bonds.
Diamond vs. Xenon solids
II. Bonding in Solids
   D. Bonding in Metals (another type of atomic
      1. Properties
          a. malleable, ductile, durable, high melting points
          make it difficult to separate metallic atoms from each
          other BUT it is easy to slide them past each other!
      2. Think of it as a SEA of ELECTRONS surrounding the
          metal cations.
   3. Alloy: a substance that contains a mixture of
    elements and has metallic properties.
       a. 2 types of alloys
           1.) Substitutional alloys
           2.) Interstitial alloys
a. Types of Alloys
   1.) substitutional alloy: some of the host
    metal atoms are replaced by another metal
       a.) brass – 67% copper & 33% zinc
       b.) sterling silver – 93% silver & 7% copper
       c.) Pewter – 85% tin, 7% copper, 6% bismuth,
        & 2% antimony
   2.) interstitial alloy – small atoms of another
    element can fit into the “holes” between the
    host metal
       a.) changes the properties
       Steel: iron with small carbon atoms embedded in
        it give strength, hardness, and make the alloy less
Examples of Interstitial Alloys
   Steel – various amounts of carbon embedded
    within the “holes” between the iron atoms

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