chemistry[1]

• States of Matter are the different forms in which matter can exist
• The three states of matter


  • Solid
  • Liquid
  • Gas
• States of Matter are the different forms in which matter can exist
• The three states of matter

  • Solid
  • Liquid
  • Gas
• Solids


  • Have a definite shape
  • Have a fixed volume
  • Particles can vibrate about their fixed positions
  • Particles are arranged regularly in a lattice
• Liquids


  • Take the shape of their container
  • Have a fixed volume
  • Particles can move past one another
  • Particles are randomly arranged
• Gases


  • Take the shape of their container
  • Have no fixed volume
  • Particles are mobile and move randomly
  • Particles are randomly arranged

  
• Boiling and Evaporation are both endothermic processes
• Boiling


  • Happens at a set temperature called the boiling point
  • Occurs throughout the liquid
  • A relatively faster process
• Evaporation


  • Occurs at any temperature below the boiling point and above the freezing point (liquid)
  • Only occurs at the surface
  • A slow process
• Condensation


  • The process by which a gas converts into a liquid
  • Happens at the same temperature as the boiling point
• Melting


  • The process in which a solid converts to a liquid
  • Happens at a set temperature called the melting point
• Freezing


  • The process in which a liquid converts to a solid
  • Happens at the same temperature as the freezing point
• Sublimation


  Occurs when a solid has enough energy to convert into a gas or gas converted into a solid
• Cooling Curve


  1. Particles of gas move slower and slower, gas contracts

  2. Particles get closer, intermolecular bonds form at condensation point

  3. Temperature stops falling, energy released cancels energy lost

  4. Once all gas turned to liquid, temperature falls again until freezing point

  5. At freezing point, intermolecular bonds form to create solid
• Heating Curve


  1. Particles of solid vibrate faster, solid expands

  2. At melting point, intermolecular bonds break

  3. Temperature remains constant until all solid turned to liquid

  4. Once all liquid, temperature rises again until boiling point

  5. At boiling point, intermolecular bonds break down to form gas

  6. Temperature remains constant until all liquid vaporised

  
• Diffusion


  The net movement of particles from a region of higher concentration to a region of lower concentration as a result of their random movement until equilibrium is reached
• The rate of diffusion is most rapid in gases > liquids > solids
• Effect of Relative Molecular Mass in Diffusion

  Molecules with a lower mass move faster on average than those with a higher mass
• Increase in external pressure


  Contraction (decrease) in volume
• Fall in external pressure


  Expansion (increase) in volume
• Temperature increase


  Increased kinetic energy of gas molecules, increased internal pressure and increased volume
• Temperature decrease


  Decreased kinetic energy of gas molecules, decreased internal pressure and decreased volume
• Elements


  A substance made of atoms that share the SAME number of protons and cannot be broken down into simpler substances by chemical methods
• Compounds


  Two or more elements chemically bonded together (in a fixed proportion)
• Mixtures


  Two or more elements not chemically bonded together
• Atom


  • Central nucleus containing neutrons and protons surrounded by electrons in shells
  • Protons have relative mass 1 and relative charge +1
  • Neutrons have relative mass 1 and relative charge 0
  • Electrons have relative mass 1/1840 and relative charge -1
  • Overall atom charge is neutral
• Proton Number (Atomic Number)


  The number of protons in the nucleus of an atom
• Nucleon Number (Mass Number)

  The total number of protons and neutrons in the nucleus of an atom
• For a neutral atom, the number of protons and electrons are equal
• Electronic Configurations


  • Electrons orbit in shells, with the first shell having a max capacity of 2 electrons and subsequent shells holding up to 8
  • Group VIII noble gases have an entire outer shell
  • The number of outer shell electrons is equal to the group number in Groups I to VII
  • The number of occupied electron shells is equal to the period number
• Isotopes


  Different atoms of the same element with the same number of protons but different numbers of neutrons
• Isotopes have the same chemical properties but different physical properties like density, boiling point and melting point
• Relative Atomic Mass


  The mass relative to the mass of a carbon-12 atom
• Metallic Bonding


  • Electrostatic attraction between positive ions in a giant metallic lattice and a "sea" of delocalised electrons
  • Good electrical conductivity
  • High melting and boiling point
  • Malleability
  • Ductility
• Diamond


  • Each carbon atom joined with four other carbon atoms
  • High melting and boiling points
  • No delocalised/free moving electrons
  • Cannot be scratched easily
  • Transparent
  • Cannot conduct electricity
  • Hard structure
  • Giant lattice arrangement
  • Used for cutting tools
• Graphite


  • Each carbon atom joined with three other carbon atoms
  • High melting and boiling points
  • Contains delocalised/free moving electrons
  • Can be scratched easily
  • Opaque/black
  • Can conduct electricity
  • Soft, layers can slide easily
  • Used as lubricant and electrode
• Silicon (IV) Oxide


  • Similar structure to diamond
  • Hard structure
  • High melting and boiling point
  • Rigid tetrahedral structure
  • Does not conduct electricity
• Covalent Bond


  Pairs of electrons shared between two atoms leading to noble gas electronic configuration (2.8.8)
• Different Types of Covalent Bonds

  • Single Bonds
  • Double Bonds
  • Triple Bonds