Solids

1
Solids

• Chapter 14 Sections 14.6-14.7

2
Review

• What is the main difference between a liquid and
  solid?
• Are most solids made of only 1 material (such as
  an element or compound) or a mixture of materials?

3
Types of Solids

• Many pure substance solids (solids made of only 1
  type of atom or 1 type of molecule) form a
  crystalline solid
• A solid with a regular arrangement of its
  components
• This produces a highly ordered structure

4
Types of Solids cont

• Salt (NaCl)
• Quartz (SiO2)
• Red Beryl (Be3Al2Si6O18)
• Zircon (ZrSiO4)

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Types of Solids cont

• There are many types of crystalline solids
• For example, sugar and salt are both solid
  crystals, and both dissolve in water
• However dissolved salt in water can conduct
  electricity and dissolved sugar cannot
• That is because salt is ionic and when it
  dissolves it is made of charged particles, sugar
  is covalently or molecular bonded and does not
  conduct electricity

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Types of Solids cont
7
Molecular representation of diamond.
8
Molecular representation of sodium chloride.
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A molecular solid.
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Types of Solids cont

• The properties of a solids are determined by the
  TYPE OF FORCES that hold the solid together

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Bonding in Solids

• Ionic solids
• Fundamental particle are ions
• Ions charged particles
• Have high melting points
• Conduct electricity well

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Bonding in Solids cont

• Molecular Solids
• Fundamental particle is a molecule (covalently
  bonded)
• Melts at low temperatures
• Because it has weaker intermolecular forces than
  ions
• Bonds that are intramolecular are stronger than
  intermolecular bonds
• Doesnt conduct electricity well

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Bonding in Solids cont

• Atomic Solids
• Fundamental particle is an atom
• Properties vary greatly
• May be atoms bonded with each other like diamonds
  (C atoms bonded with other C atoms, like a GIANT
  molecule)
• May have little interaction with each other, like
  xenon

14
Bonding in Solids cont

• Bonding in Metals
• Metals have very unique properties
• They are ductile (can be pulled into wires)
• They are malleable (can be hammered into shaped)
• They conduct electricity
• The properties indicate that it is hard to
  separate metal atoms , but easy to move them past
  each other
• We call these bonds strong but non-directional

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Bonding in Solids cont

• Bonding in metals
• The model we use to describe metallic bonds is
  called the electron sea model
• This describes the metal atoms in a varying sea
  of valance electrons

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Bonding in Solids cont

• The electron sea model explains the easy
  conduction of electricity
• That atoms can be moved easily but cannot
  separate

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Bonding in Solids cont

• Because of the nature of metallic bonds, it is
  easy to make an alloy
• An alloy is a substance that contains mixture of
  elements that have metallic properties.
• There are two types of alloys
• Substitutional alloy
• Interstitial alloy

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Bonding in Solids cont

• Substitutional alloys
• Some of the atoms of the host metal are replaced
  by other metals atoms of similar sizes
• Example brass, sterling silver, pewter

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Bonding in Solids cont

• Interstitial alloy
• Formed when some of the interstices (holes)
  between metal atoms are filled with smaller atoms
• Examples Steel

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Bonding in Solids cont

• You should be able to determine the type of
  crystalline solid by looking at a substance
• Ammonia (NH3)
• Molecular Solid
• Calcium Oxide (CaO)
• Ionic Solid
• Krypton (K)
• Atomic Solid
• Gold (Au)
• Metallic solid

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Homework

• Read pages 454-461, problems 1-3 on 461. And
  problems 43-52 on 465
• Pre-Laboratory Questions for Lab 55 on page 195
  of your lab book