chem

• Matter

  Anything that has mass & occupies space (has volume)
• Density


  Measurement of how tightly a material is packed together, defined as mass per unit volume
• Law of Conservation of Mass: states that mass cannot be created or destroyed but is transformed from one form to another
• Atoms


  The "building blocks" of matter, the simplest form of matter that cannot be broken down further (has a nucleus with electrons orbiting around it in shells)

  
• Elements


  The purest form of a substance which consists of only one type of atom
• Molecules


  Consist of 2 or more atoms (same or different element) that are chemically combined
• Compounds


  2 or more elements/compounds chemically bonded in fixed/definite proportions
• All compounds are molecules, but not all molecules are compounds
• Mixtures


  2 or more elements or compounds that are mixed together but do not chemically bond
• Homogeneous mixtures


  Have uniform composition throughout the structure
• Heterogeneous mixtures


  Do not have uniform composition in their structure (uneven)
• Pure substances


  • Made up of only one type of atom or molecule with a fixed structure
  • Fixed melting and boiling point
  • Subdivided into elements and compounds
  • Homogeneous chemical composition
  • Cannot be broken into simpler substances
• Impure substances


  • Made up of a combination of different atoms/molecules & has no fixed structure
  • Melting and boiling point range
  • Subdivided into homogeneous and heterogeneous mixtures
  • Varying or heterogeneous composition
  • Can be broken down into purer forms through separation/purification techniques
• Solids


  Have a fixed shape & volume, highest intermolecular force of attraction due to closely packed particles, movement of particles is restricted (can only vibrate), cannot be compressed, rate of diffusion is very slow
• Liquids


  Have a fixed volume but not a fixed shape, take the shape of the container, moderate intermolecular force of attraction as particles are slightly loosely packed and can move, difficult to compress, rate of diffusion is higher than solids
• Gases


  Have neither a fixed shape or volume, weak intermolecular force of attraction as particles are far apart and move freely, most compressible state, highest rate of diffusion, highest kinetic energy
• STP (Standard Temperature and Pressure)

  Conditions used in chemistry to compare different properties of gases, 0 degrees Celsius and 1 atmosphere pressure, 1 mol of gas is 22.4 litres of volume
• Solid to Liquid (Melting)


  Particles in solid absorb heat energy, vibrate more, bonds holding them in fixed position weaken, particles gain enough kinetic energy to overcome attractive forces and transition to liquid state
• Liquid to Gas (Vaporization/Evaporation)

  Particles in liquid gain more kinetic energy from heat, some at surface gain enough to overcome attractive forces and escape into gas phase (evaporation), if heat input is sufficient, entire liquid transitions to gas phase (vaporization)
• Solid to Gas (Sublimation)

  Substance's vapour pressure exceeds atmospheric pressure at its melting point, particles in solid gain enough kinetic energy to break free and enter gas phase without passing through liquid
• Gas to Liquid (Condensation)

  Gas particles lose kinetic energy (usually by cooling), attractive forces between them overcome their motion, causing them to come closer together and form liquid droplets
• Liquid to Solid (Freezing/Solidification)

  Liquid particles lose kinetic energy (by cooling), attractive forces pull them into fixed positions, forming solid structure
• Gas to Solid (Deposition)

  Gas particles lose kinetic energy (by cooling), attractive forces pull them together to form solid structure, gas transitions directly to solid without going through liquid phase
• Kinetic Theory of Matter


  Model that helps understand behaviour of gases, based on idea that matter is made up of small particles (atoms, molecules) always in motion, properties of matter determined by how particles move and interact
• Assumptions of Kinetic Theory

  • Gas particles are tiny
  • Gas particles have constant random motion
  • Elastic collisions between particles
  • No attraction or repulsion between particles
  • Relation between temperature and particle kinetic energy
• Real life examples of Kinetic Theory


  • Smelling perfume
  • Inflating a tire
  • Hot air balloon
• Displacement


  When a more reactive element displaces or pushes out a less reactive element from a compound
• Mass


  Measure of how much matter an object contains
• Volume


  The amount in a 3D space
• Density


  Mass of a unit of a mattered substance
• Atom

  Smallest particle of a chemical that can exist
• Element


  Types of atoms that have the same number of protons in their nuclei

  
• Compound


  Made of several elements chemically bonded together
• Mixture


  A material that is made up of 2 or more chemicals which aren't chemically bonded
• Homogeneous


  Can dissolve in water
• Heterogeneous


  Doesn't dissolve in water
• Cohesion


  Force of attraction between the molecules of the same substance
• Explain why some metals react with water, while others do not.
• Describe how to test whether an unknown metal reacts with dilute sulfuric acid using litmus paper as an indicator.
• Adhesion


  Force of attraction between the molecules of different substances