term 2

• Elements

  • Materials made up of elements
  • All elements are found on the periodic table
• Periodic table


  • Horizontal rows are periods
  • Vertical columns are groups
  • Elements in the same group have the same chemical properties
• Types of elements


  • Metals
  • Semi-metals/metalloids
  • Non-metals
• Position on periodic table

  • Left of dividing line are metals
  • Right of dividing line are non-metals
  • Either side of dividing line are metalloids (semi-metals)
• Transition metals


  • Group 3 to 13
• Diatomic elements


  • Hydrogen
  • Nitrogen
  • Oxygen
  • Fluorine
  • Chlorine
  • Bromine
  • Iodine
• Groups on periodic table

  • Alkali metals
  • Alkali earth metals
  • Group 17 - halogens
  • Group 18 - noble gases
• Atomic number (Z)


  Number of protons and electrons
• Mass number (A)


  Number of protons and neutrons
• Elements are arranged systematically according to increasing atomic numbers
• Compound

  Formed when atoms bond chemically
• Chemical formula


  Shows the elements and ratio in which they bond
• Elements on the far left of the periodic table are usually named first in a compound
• Common names

  • Sodium chloride = Table salt
  • Hydrogen oxide = Water
  • Hydrogen chloride = Hydrochloric acid
• Compounds with common groups of elements have similar names
• Common groups of compounds

  • Hydroxide
  • Nitrate
  • Sulphate
  • Phosphate
  • Sulphite
  • Carbonate
• Chemical reaction


  Process where one set of chemical substances is changed into a new set with different properties
• Reactants


  Substances that react with each other
• Products


  New substances that form
• Chemical equations represent reactions using symbols and formulas
• Chemical equations must be balanced - same number of atoms of each element on both sides
• Indicator


  Chemical substance that changes colour when it reacts with an acid or base
• Indicator colours


  • Red in acid
  • Blue in alkali/base
  • Purple in neutral
• pH scale


  Measures concentration of hydrogen ions, ranges from 0-14
• Metals react with oxygen to form metal oxides (basic oxides)
• Non-metals react with oxygen to form non-metal oxides (acidic oxides)
• Rust


  Iron oxide formed by reaction of iron with oxygen and water
• Factors affecting rate of rusting

  • Salts in water
  • Acidic conditions
  • Impurities in iron
  • Amount of oxygen
  • Proximity to sea
• Methods to prevent rusting

  • Spraying with oil
  • Painting
  • Spraying with rust preventative
  • Galvanizing
  • Chroming
  • Electroplating
• Non-metals are usually brittle and dull in appearance
• Acid


  Tastes sour, can corrode, changes indicator colours, neutralises bases
• Concentrated acids are very dangerous
• Base


  Feels soapy, tastes bitter, changes indicator colours, neutralises acids
• Reaction between acid and metal is exothermic (releases heat)
• Salts formed from different acids

  • Chloride
  • Nitrate
  • Sulphate
  • Acetate
• Neutralisation is a reaction between an acid and a base to form a salt and water
• Neutralisation is exothermic (releases heat)
• Metal oxides react with acids to form salts and water
• Metal hydroxides react with acids to form salts and water
• Acid + metal carbonate -> salt + water + carbon dioxide