chemistry ch 2

• Matter


  Made up of tiny particles, has mass and takes up space
• States of matter

  • Solid
  • Liquid
  • Gas
  • Plasma
• Solids


  • Particles packed very tightly together with strong forces between one another
  • Little freedom of movement, can vibrate about a fixed position
  • Have definite volume and shape
• Liquids


  • Particles not fixed in any definite positions
  • Able to move freely throughout the liquid but not as independently as gases
  • Have definite volume but no definite shape
• Gases


  • Particles in constant and rapid motion due to weak attractive forces
  • Move freely in all directions until they hit the walls of the container
  • Do not have a definite volume and shape of their own
• Brownian motion


  Continuous random movement of small particles suspended in a gas or liquid, arising from collisions with the gas or liquid particles
• Diffusion process


  Particles of one substance mix with and move through the particles of another substance
• Factors affecting speed of diffusion

  • Mass of particles (bigger mass = slower diffusion, smaller mass = faster diffusion)
  • Temperature (higher temperature = faster diffusion)
• Physical changes

  • Melting
  • Boiling
  • Freezing
  • Evaporation
  • Vaporisation
  • Condensation
  • Sublimation
  • Dissolving
  • Cutting
  • Moulding
• Melting point

  Temperature at which a solid changes to a liquid state at one atmospheric pressure
• Boiling point

  Temperature at which the vapour pressure of the liquid is equal to the atmospheric pressure of the surrounding
• Vaporisation

  Process of a chemical or element being converted from a liquid to a vapour
• Evaporation


  Process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure
• Boiling

  Rapid vaporisation of a liquid, which occurs when a liquid is heated to its boiling point
• Freezing

  Process in which a liquid becomes sufficiently cold to change into a solid
• Freezing point

  Temperature at which a liquid becomes a solid
• Condensation

  Change from a gaseous state to its liquid state
• Sublimation

  Change of solid state directly into gaseous state without melting
• Deposition

  Direct solidification of a vapour by cooling, the reverse of sublimation
• Chemical change

  Change in which one or more new substances are formed
• Element


  Substance that cannot be broken down into other simpler substances by chemical means
• States of elements

  • Solid
  • Liquid
  • Gas
• Metals

  • Show metallic luster
  • Have high density
  • Most are malleable and ductile
  • Good conductors of heat and electricity
• Non-metals

  • Do not show metallic luster
  • Have low density
  • Usually brittle
  • Poor conductors of heat and electricity
• Compound

  Substance containing two or more different elements chemically joined together in a fixed ratio
• Molecule

  Simplest unit of a chemical substance, usually a group of two or more atoms
• Types of molecules

  • Diatomic (two atoms)
  • Triatomic (three atoms)
  • Polyatomic (three or more atoms)
• Binary compound

  Compound formed by the combination of two elements
• Ternary compound


  Compound formed by the combination of three elements
• Molecule of an element


  Consists of atoms of the same kind
• Molecule of a compound


  Consists of more than one kind of atoms, combined in a definite ratio
• Types of molecules

  • Diatomic
  • Triatomic
  • Polyatomic
• Diatomic molecule

  Molecule composed of only two atoms of same or different elements
• Triatomic molecule

  Molecule composed of only three atoms of same or different elements
• Polyatomic molecule

  Molecule composed of three or more atoms of same or different elements
• Binary compound

  Compounds formed by the combination of two elements
• Ternary compound


  Compounds formed by the combination of three elements
• The most obvious difference is that an element cannot be broken down into other substances by chemical means where as a compound can be broken down into other substances by chemical means
• Mixture


  A combination of more than one substance, where these substances are not bonded to each other
• Heterogeneous mixture


  A non-uniform mixture where the different components can be seen