Topic 2- Bonding, structure and the properties of matter

• states of matter properties

  A) solid

  B) liquid

  C) gas

  D) regular

  E) random

  F) random

  G) vibrate around a fixed position

  H) move around each other

  I) move quickly in all directions

  J) very close

  K) close

  L) far apart

  
• summary of state changes

  A) solid to liquid

  B) liquid to gas

  C) liquid to solid

  D) liquid to gas

  E) gas to liquid

  F) solid to gas

  
• Particle theory

  • The stronger the forces between the particles, the higher the energy needed for melting and boiling to occur
  • When substances are heated, the particles absorb thermal energy which is converted into kinetic energy
  • Heating a solid causes its particles to vibrate more and as the temperature increases, they vibrate so much that the solid expands until the bonds break and the solid melts
  • On further heating, the now liquid substance expands more and some particles at the surface gain sufficient energy to overcome the intermolecular forces and evaporate
• •  latent heat
  • While changing state, the temperature of the substance remains the same as the heat energy goes into breaking the bonds between the particles
• limitations of the particle theory

  • Particle theory considers all particles, irrespective of their state or chemical identity, to be small, solid and inelastic
  • It doesn’t consider the difference caused by different particles, such as atoms, ions or molecules or mixtures of all three
  • The theory also fails to consider the intermolecular forces that exist between different particles in different substances
• Physical Properties of Ionic Compounds

  • Ionic compounds are made of charged particles called ions which form a giant lattice structure
  • Ionic substances have high melting and boiling points due to the presence of strong electrostatic forces acting between the oppositely charged ions
  • These forces act in all directions and a lot of energy is required to overcome them
  • The greater the charge on the ions, the stronger the electrostatic forces and the higher the melting point will be
• electrical conductivity of ionic compounds

  • For electrical current to flow there must be freely moving charged particles such as electrons or ions present 
  • Ionic compounds can conduct electricity in the molten state or in solution as they have ions that can move and carry charge
  • They cannot conduct electricity in the solid state as the ions are in fixed positions within the lattice and are unable to move
• Melting and boiling points: small molecules

  • Small molecules are compounds made up of molecules that contain just a few atoms covalently bonded together
  • They have low melting and boiling points
  • This is due to the weak intermolecular forces that require little energy to overcome
  • Some can dissolve in water, by forming intermolecular attractions with the water molecules
  • As the molecules increase in size, the melting and boiling points generally increase

• Intermolecular Forces Vs. Covalent Bonds

  • Small molecules have covalent bonds joining the atoms together, but intermolecular forces that act between molecules
  • They have low melting and boiling points
  • These forces are very weak when compared to the covalent bonds and so most small molecules are either gases or liquids at room temperature
  • As the molecules increase in size the intermolecular forces also increase as there are more electrons available
  • This causes the melting and boiling points to increase
• Properties: Giant Covalent Substances

  • They have high melting and boiling points as they have many strong covalent bonds
  • Large amounts of heat energy are needed to overcome these forces and break down bonds
  • Most cannot conduct electricity as they do not have free electrons nor charged particles but there are some exceptions such as graphite and graphene
• • Allotropes of carbon

  A) Very high

  B) Very high

  C) Low

  D) Very high

  E) Very high

  F) none

  G) good

  H) semi

  I) very good

  J) none

  K) Transparent crystals

  L) Grey/ black solid

  M) yellow solid

  N) transparent sheets

  O) transparent crystals

  P) very flexible and strong

  Q) very light and strong

  R) soft and slippery

  S) hardest naturally occurng substace

  T) produces electrical charge from mechanical stress

  
• Properties of Metals


  • Metallic bonds are very strong and are a result of the attraction between the positive metal ions and the negative delocalised  electrons within the metal lattice structure
  •  very high melting and boiling points and are solids at room temperature
  • They are usually insoluble in water although some do react with it
  • Metals are good conductors of heat and electricity due to the delocalised electrons
  • The layers of atoms in metals can slide over each other meaning metals are malleable and can be hammered and bent into shapes or rolled into flat sheets
• Properties of alloys


  • often have properties that can be very different to the metals they contain, for example, they can have greater strength/ hardness or resistance to corrosion/ extreme temperatures
  • Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms
  • This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal
  • Brass > 70% copper and 30% zinc
• Alloys


  • Alloys are mixtures of metals, where the metals are mixed together physically but are not chemically combined
  • They can also be made from metals mixed with non-metals such as carbon
• Metals have delocalised electrons available to move and carry charge through the metal lattice structure

  • Hence electrons can flow so electricity is conducted
  • copper- great conductor and malleable