c3

• Elements

  The basic building blocks of all living and non-living matter
• Elements


  Substances that cannot be broken down into simpler substances
• Element symbols

  Unique to prevent confusion and for standardization (e.g. Fe for iron, C for carbon, O for oxygen, N for nitrogen)
• Element symbols are written with the first letter capitalized and the second letter in lowercase
• Periodic table of elements

  • Elements are arranged based on their properties (metals vs non-metals)
  • Elements usually occur naturally as solids, liquids or gases
  • 11 elements are gases
  • 2 elements are liquids (mercury and bromine)
  • The rest are solids at room temperature
• The diversity of matter is made up of one or more elements from the periodic table
• Metals

  • Have a shiny appearance
  • Are malleable (can be beaten into sheets)
  • Are ductile (can be drawn into wires)
  • Have high melting and boiling points
  • Are good conductors of heat and electricity
• Non-metals

  • Have a dull appearance
  • Are brittle (easily broken)
  • Have low melting and boiling points
  • Are poor conductors of heat and electricity
• Compound

  A substance made up of two or more different elements chemically combined together
• Compounds

  • Do not have the same properties as their constituent elements
  • Form through a chemical reaction
  • Have a fixed proportion of constituent elements by mass
  • Cannot be easily separated into constituent elements
• Mixture

  Made up of two or more elements and/or compounds that are not chemically bonded
• Mixtures

  • Have the same characteristics as their constituents
  • Have no fixed proportion of constituents
  • Form without a chemical reaction
  • Can be easily separated by physical methods
• Solution

  A mixture in which one substance (solute) completely dissolves in another substance (solvent)
• Solutions

  • Constituent particles are mixed evenly
  • Solute particles are too small to be seen and can pass through filter paper
  • Can be described as dilute or concentrated based on the amount of solute in the same volume of solvent
• Solvent particles

  They spread evenly throughout the whole solution
• Solute or solute particles


  They are too small and cannot be seen, and can pass through the filter paper easily
• Filtration is not the best physical method to separate salt particles from water particles because the salt particles are smaller than the filter paper holes and will pass through
• Dilute solution

  Contains less solute (e.g. less salt) for the same volume of solvent
• Concentrated solution


  Contains more solute (e.g. more salt) for the same volume of solvent
• Suspension


  A mixture of insoluble substances in a liquid or gas
• What happens when a suspension is left to stand

  The solid particles will settle to the bottom of the mixture
• Residue


  The solid particles left on the filter paper when a suspension is filtered
• Filtrate


  The liquid part of the suspension that passes through the filter paper
• When a suspension is filtered, the solid particles form the residue and the liquid filtrate may contain dissolved solute
• Evaporation setup

  1. Evaporating dish

  2. Wire gauze

  3. Tripod stand

  4. Bunsen burner
• After evaporation, the salt is left at the bottom of the evaporating dish
• Differences between solutions and suspensions

  • Solutions are homogeneous, suspensions are heterogeneous
  • In solutions, solute does not separate from solvent, in suspensions insoluble solids settle
  • In solutions, no filter particles remain, in suspensions insoluble solids are obtained on the filter paper
  • In solutions, light can pass through fully, in suspensions light cannot pass through fully
• Solubility

  How well a solute dissolves in a fixed volume of a particular solvent
• Factors affecting solubility

  • Nature of the solute
  • Nature of the solvent
  • Temperature (solubility increases with increase in temperature)
• Rate of dissolving

  How fast a solute dissolves in a solvent
• Factors affecting rate of dissolving

  • Temperature (higher temperature, faster dissolving)
  • Size of solid particles (smaller particles, faster dissolving)
  • Rate of stirring (faster stirring, faster dissolving)
• Distinguishing elements, compounds and mixtures

  • Composition: Elements - one element, Compounds - two or more elements, Mixtures - two or more different elements and compounds
  • Properties: Elements - none, Compounds - different from constituents, Mixtures - similar to constituents
  • Proportion of constituents: Elements - none, Compounds - fixed, Mixtures - not fixed
  • Formation: Elements - mostly natural, Compounds - chemical reaction, Mixtures - physical change
  • Separation: Elements - can't separate, Compounds - chemical means, Mixtures - physical means