States of Matter

• Matter


  Anything that has mass and occupy space or volume
• States of matter


  • Solid
  • Liquid
  • Gas
  • Plasma
  • Bose-Einstein condensate
  • Neutron stars
• Discussions will be based on only the first three state of matter
• Kinetic theory of matter (kinetic molecular theory)


  Theory used to explain why matter exist in different states/phases and how matter can change from one state/phase to the other
• Postulates of kinetic theory of matter

  • Matter is made up tiny particles (ie atoms, molecules or ions) which are in constant motion
  • These particles possess kinetic energy as a result of their motion
• Lattice


  Ordered arrangement (regular pattern) of the components (atoms, molecules or ions) which make up a sold in three dimension
• Lattice point


  Position of an atom, ion or molecule in a solid crystal
• Unit cell


  Identical building blocks in the three dimensional lattice structure of the solid
• Types of unit cells (shapes of solids)

  • Simple cubic system or lattice
  • Face-centred cubic system
  • Body centred cubic system
• Types of solids


  • Metallic solids
  • Ionic solids
  • Molecular solids
  • Macromolecular/Giant Covalent solids
• Metallic solids


  Each atom donates their outer electron(s) to form a pool or sea of delocalized electrons and the metal become a fixed cation. There is an electrostatic forces of attraction between this fixed metal cation and the delocalized electrons
• Properties of metallic solids


  • Good conductors of heat and electricity
  • Form alloys readily
  • Have high melting point
  • Malleable and ductile
  • Have a characteristic metallic luster
• Ionic solids


  Consist of positive ions and negative ions, these ions occupy lattice point that is held together by electrostatic forces of attraction
• Properties of ionic solids

  • Have high melting point
  • Conduct electricity in the molten or aqueous state
  • Brittle
  • Soluble in polar solvents such as water
• Molecular solids

  Molecules consisting of discrete molecules at their lattice points. Their atomic bonds are basically covalent bonds with their intermolecular bonds been Van der Waals forces or hydrogen bonding
• Properties of molecular solids

  • Poor conductors of heat and electricity
  • Soft with low melting point
  • Low densities
  • Soluble in organic solvent (ie non-polar solvent)
• Macromolecular solids / giant covalent solids

  Molecules whose atoms are held together by covalent bonds in an extensive 3-dimension network
• Properties of macromolecular solids

  • Insoluble in both polar and non-polar solvent
  • Have high melting and boiling points
  • Bad conductors of electricity except graphite
  • Crystalline and hard solids at room temperature
• Allotropy

  Existence of an element in different forms in the same physical state
• Allotropes

  Two or more forms of the same element that differ significantly in chemical and physical properties and also in their basic molecular structure
• Structure of diamond


  Allotrope of carbon with sp3 hybridized carbon atoms, each carbon atom tetrahedrally surrounded by four other carbons, linked into a 3-dimension giant covalent network

  
• Uses of diamond


  • Used as jewellery
  • Used in the manufacture of safety glass for dangerous explosion
  • Used in the industrial manufacture of drills or used as abrasive powder for cutting and polishing
• Structure of graphite


  Composed of a flat two-dimensional sheet of carbon atoms, each carbon atom covalently bonded to three other atoms in the plane, the carbon atoms are sp2 hybridized with unhybridized p-orbital on each carbon atom, arranged in six member rings (hexagonal rings) forming parallel plates (graphenes)

  
• Uses of graphite

  • Used as lubricant due to its ability to slide over each other and low friction
  • Used in the manufacture of crucibles for high temperature experiment due to its high thermal conductivity
  • Used as a moderator in nuclear reactors due to its high resistance to neutron radiation
  • Used as electrodes in electrolysis due to its delocalized electrons
• Uses of iodine in everyday life

  • Used as antiseptic
  • Used to detect and locate brain tumor, goiter, and kidney blockage
  • Vital constituent of the thyroid hormone thyroxin
  • AgI used for photographic films and cloud seeding
• Liquid state

  Particles in liquids are held slightly far apart, can move past one another, perform transition, vibration and rotation motions, held together by weak Van der Waal forces and hydrogen bonding
• Characteristic and nature of liquids

  • Have no fixed shape but have volume
  • Have a relatively high rate of diffusion
  • Cannot be compressed
  • Have the ability to flow
  • Have slightly weak attractive force
• Saturated vapour pressure

  Pressure exerted by a vapour in equilibrium with a liquid at a given temperature, where the rate of evaporation is equal to the rate of condensation
• Boiling point (normal boiling point)

  Temperature at which the vapour pressure of a liquid is equal to the prevailing or surrounding atmospheric pressure
• Factors that affect the boiling point

  • Atmospheric pressure
  • Type of attractive forces between the liquid molecules
  • Presence of impurities (non-volatile solute)
• Vapour vs gas


  Gas refers to a substance that has a single defined thermodynamic state at room temperature, whereas a vapour refers to a substance that is a mixture of two phases at room temperature
• Determination of boiling point of ethanol

  Half-fill boiling tube with ethanol, add granules, place glass tubing at top, heat gently using water bath, record highest constant temperature
• Boiling point

  Indicates the strength of the intermolecular cohesive forces in a liquid
• Gas

  A substance that has a single defined thermodynamic state (or exist in a single phase) at room temperature
• Vapour

  A substance that is a mixture of two phases (gaseous and liquid) at room temperature
• Determination of boiling point of ethanol

  1. Half-fill boiling tube with ethanol

  2. Add granules to avoid bumping

  3. Place glass tubing at top for condensation

  4. Heat gently using water bath

  5. Record highest constant temperature
• Ethanol is volatile and can catch fire easily, so great care should be taken when measuring its boiling point
• Pure ethanol boils at 78°C, but impurities can cause a slight increase in the boiling point
• Determination of boiling point of water

  1. Put water in a clean beaker

  2. Heat the water to boiling over Bunsen flame

  3. Read and record the highest constant temperature
• If the water is pure or distilled, it will boil at 100°C, but if it is tap water, it will boil at a slightly higher temperature