NS nothes

• Elements


  Consist of one type of atom and are found on the Periodic Table
• Atomic number (Z)


  Number of protons in the nucleus
• In a neutral atom, the number of protons = number of electrons
• Chemical reaction


  A process during which one set of chemical substances is changed into a new set of chemical substances with different chemical properties
• Factors influencing the rate of rust

  • Salt water (faster)
  • Low pH - more acidic conditions (faster)
  • Impurities in iron (slower)
  • Amount of oxygen in contact with exposed surface (faster)
• Methods to prevent rust

  • Protect iron from water and moisture (spray with oil, paint, rust preventative)
  • Connect a strip of a more reactive metal (magnesium or zinc) to the iron
  • Galvanize - cover with another metal that does not rust easily
  • Cover with a metal that does not corrode (chrome, zinc, tin)
• Non-metal oxide


  The product that forms if non-metals react with oxygen, also known as acidic oxides
• Properties of acids


  • Taste sour
  • Can corrode other substances
  • Can be weak or strong
  • Can change the color of other substances
  • Change the color of indicators (e.g. litmus turns pink)
  • Can neutralize a base
  • Dissolve easily in water
  • Can be diluted by adding to water slowly
• Properties of bases


  • Feel soapy
  • Taste bitter
  • Can be weak or strong
  • Can change the color of other substances
  • Change the color of indicators (e.g. litmus turns blue)
  • Can neutralize an acid
• Reactions of acids


  1. Acid + metal → metal oxide + hydrogen

  2. Acid + metal hydroxide → salt + water

  3. Acid + metal oxide → salt + water

  4. Acid + metal carbonate → salt + water + carbon dioxide gas
• Neutralization


  A reaction between an acid and a base that produces a salt and water, and is an exothermic reaction
• To test for carbon dioxide, bubble the gas through clear limewater - if it turns milky, it is carbon dioxide
• Acids in the school laboratory may burst
• Diluting an acid


  1. Add concentrated acid little by little to water

  2. Never add water to the acid!
• Common acids used in the school laboratory

  • Hydrogen sulfate (Sulfuric acid)
  • Hydrogen nitrate (Nitric acid)
  • Hydrogen chloride (Hydrochloric acid)
  • Ethanoic acid (Acetic acid, vinegar)
• Base


  Formed when a metal burns in oxygen to form a metal oxide, or a metal oxide dissolves in water to form a metal hydroxide
• The bright red Natron Lake in To-- is an example of a natural indicator
• Indicator


  Chemical substance which changes colour when it reacts with an acid or an alkali
• Acid solution at room temperature has a pH value lower than 7, alkaline solution has a pH value greater than 7, neutral solutions have a pH equal to 7
• Chemical reaction


  Process during which one set of chemical substances is changed into a new set of chemical substances
• Common names of some compounds

  • H2O (Water)
  • NaHCO3 (Baking soda)
  • OH- (Hydroxide)
  • NO3- (Nitrate)
  • NH3 (Ammonia)
  • Na2CO3 (Washing soda)
  • SO4^2- (Sulfate)
  • H2SO4 (Sulfuric acid)
  • KNO3 (Saltpetre)
  • CO3^2- (Carbonate)
  • HNO3 (Nitric acid)
  • KOH (Caustic potash)
  • PO4^3- (Phosphate)
  • H2CO3 (Carbonic acid)
  • CaCO3 (Marble)
  • SO3^2- (Sulfite)
  • NaCl (Table salt)
  • CaSO4 (Gypsum)
  • CO2 (Carbon dioxide gas)
  • CH4 (Natural gas)
  • HCl (Hydrochloric acid)
• Products


  New substances that form
• Oxygen gas exists in nature as a diatomic molecule, O2
• Diatomic elements


  • Hydrogen (H2)
  • Oxygen (O2)
  • Chlorine (Cl2)
  • Iodine (I2)
  • Nitrogen (N2)
  • Fluorine (F2)
  • Bromine (Br2)