Chemistry gcse chapter 1-3 and 20

• In a solid:

  • particles are very close
  • particles are arranged in an orderly manner, and very close
  • the particles vibrate in one place
  • their kinetic energy is very low
• In a liquid:

  • particles are close
  • particles have an irregular arrangement
  • the particles move around each other
  • their kinetic energy is high
• In a gas:

  • particles are far
  • particles have an irregular arrangement
  • the particles move randomly and vigorously
  • their kinetic energy is very high
• A solid:

  • cannot be compressed
  • definite volume and shape
  • particles are compact
  • particles vibrate in fixed positions
• A liquid:

  • cannot be compressed
  • can flow
  • definite volume
  • particles move randomly
• A gas:

  • particles are far apart
  • can flow
  • particles move randomly
• solid -> liquid = melting

  liquid -> solid = freezing

  liquid -> gas = evaporation

  gas -> liquid = condensation

  solid -> gas = sublimination

  gas -> solid = deposition

  
  

  example of sublimination -> dry ice

  example of deposition -> frost forming on the ground
• The kinetic particle theory state that:

  • the particles in a solid have a strong attraction and are unable to move freely as they only have a little kinetic energy to vibrate in one spot
  • the particles in a liquid have a weaker attraction and can move freely as they have enough energy to move around randomly
  • the particles in a gas have a very weak attraction and can move freely as they have a high kinetic energy
  • all matter is made of particles
• Gas does not have a fixed volume, is is easily compressed as there is so much space between the particles
• the higher the temperature, the more the kinetic energy, the higher the volume of gas
• g - gas

  l - liquid

  s - solid

  aq - aqueous

  (a solution or mixture where water is the solvent)
• For a solid to melt:

  • particles will be able to break free from their attraction
  • particles will gain energy to move freely
  • energy will be input
• for a liquid to freeze

  • particles will slow down and lose kinetic energy
  • the attraction will increase between particles
  • energy will be output
• particles go from an area of high concentration to an area of low concentration, this happens in both liquids and gases.

  equilibrium is when particles have the same concentration in an enclosed area (happens over time)

  the higher the temperature, the more kinetic energy, the more particles move around, which also means the rate of diffusion increases
• relative atomic mass -> no of protons + neutrons
• volumetric pipette - used to measure a specific volume

  
• burette - accurate to 0.15cm^3

  
• volumetric flask - used to measure a specific volume

  
• 1kg = 1000g

  1cm^3 = 1ml

  dm^3 = 1000cm^3 = 1L
• Molecules

  • non-metal atoms chemically combine to create molecules
  • can be elements or compounds
  • diatomic
  • weak attractions, little energy required to break
  • the bigger the molecule the bigger the force of attraction
  • low melting and boiling points
• Atoms

  • single atoms -> noble gases (monatomic)
  • weak attractions, little energy needed to break
  • low boiling and melting points
  • each element is made up of one type of atom
  • smalest particles that represents an element
  • contains electrons, protons and neutrons
• compounds

  • two or more elements chemically bonded
  • cannot be separated by physical methods, only chemical methods
  • strength of attraction depends on the type of particle and chemical bond
  • pure substances
• ions

  • non-metal atoms always gain outer shell electrons to become negatively charged ions
  • atoms who gained or lost electrons
  • metal atoms always lose outer shell electrons to become positively charged ions
  • strong attraction, opposites attract
  • the bigger the charge and the smaller the ion, the bigger the attraction
• Molecule

  • 2 or more atoms chemically bonded

  Compound

  • 2 or more different type of atoms bonded together

  Elements

  • one type of atom (monatomic or diatomic)

  monatomic

  • singular atom

  diatomic

  • pair of atoms

  mixture

  • combination of elements and/or compounds which can be seperated

  binary compound

  • consists of exactly 2 different atoms which are chemically bonded
• calculating the Rf (retention factor) of a chromatogram:

  
  

  distance travelled by the compound/distance travelled by the solvent front
• the higher a solute travels, the more soluble it is
• solvent as a substance that dissolves a solute
• solute as a substance that is dissolved in a solvent
• solution as a mixture of one or more solutes
• saturated solution is when a solute is unable to dissolve in the solvent (maximum concentration of solute in solvent)
• filtrate as a liquid or solution that has passed through a filter
• residue as a substance that remains after evaporation, distillation, filtration or any similar process
• to purify for example rocksalt,

  1. mix the rocksalt with distilled water until it turns into a saturated solution
  2. filter out impurities from the solution using a filter paper
  3. heat the filtrate until it is hot
  4. take filtrate off the heat and allow to evaporate until crystals form

  
  

  longer time taken to evaporate results in bigger crystals

  filtration -> evaporation to dryness -> crystallisation
• process of simple distillation

  1. The liquid is heated so it boils and turns into a gas
  2. The gas is then cooled in the condenser and turns back into a liquid
  3. The liquid runs down the condenser
  4. The solute stays in the flask
• process of fractional distillation with 2 or more liquids with different boiling points

  1. The liquid is heated so it boils and turns into a gas
  2. The gas flows upward through a fractioning column, the liquid with the higher boiling point condenses here and falls back into the flask
  3. the gas of the liquid that has a lower boiling point reaches the upper part of the column, (the temperature of this gas can be read with the thermometer on the top)
  4. the gas at the top then goes through a condenser and into a separate flask.

  An example of fractional distillation is separating crude oil.