science notes chap 3

• periodic table of elements

  elements are arranged based on their properties

  left of staircase: metals

  right of staircase: non-metals
• elements

  elements are basic building blocks of living and non-living matter

  elements cannot be broken down into simpler substances
• physical properties

  qualities that can be observed and measured without changing its composition

  example: colour transparency and texture
• compounds

  a compound consists of two or more elements that are chemically combined
• properties of compounds 


  -a compound does not have the same ( different ) properties as their constituents elements

  -constituents elements of a compound are always chemically combined in a fixed proportion by mass

  -a compound cannot be separated into its constituents easily
• mass


  amount of matter in a object

  SI unit is kilograms ( kg )
• volume


  amount of space an object takes up

  SI units is cubic metre ( \m3 )
• rate of dissolving 


  refers to how quickly a solute dissolves in a solvent
• mixtures 


  a mixture is made up of two or more substances ( different elements , different compounds , different elements or compounds ) that are not chemically combined
• properties of mixtures 


  -a mixture has the same characteristics as its consituents

  -constituents of mixtures do not have a fixed proportion

  -consituents of a mixture can be easily separated using physical methods
• suspension 


  a suspension is a mixture that contains insoluble substances in a solvent
• properties of a suspension

  -insoluble substances can be seen

  -light cannot pass through fully

  -insoluble substances settle to form solid deposits
• solutions 


  a solution is a mixture in which one substance dissolves completely in another substance
• properties of solutions

  -particles of the solute cannot be seen

  -light can pass through fully

  -solute doesnt settle to form solid deposits
• factors affecting the rate of dissolving

  1.temperature of solvent

  higher temperature - higher rate of dissolving

  2.size of solute particles

  small solute size - higher rate of dissolving

  3.rate of stirring

  fast rate of stirring - higher rate of dissolving
• solubility 


  how well a solute dissolves in a fixed volume of a particular solvent
• properties of solubility 


  1.type of solvent

  -the same solute may not be soluble in differnt solvents

  -differnt solutes may not be soluble in the same solvent