A

• physical changes

  A physical change modifies the appearance or form of the substance but it does not turn it into another. The substance stays the same.

  For example, the melting and boiling point are physical properties
• The general formula is used to represent all possible compounds containing the elements involved. For example, H2O represents water (H2O) as well as hydrogen peroxide (H2O2).
• Chemical change

  A chemical change occurs in a chemical reaction and produces a new chemical substance.

  We can identify a chemical change (reaction) if we observe a color change, formation of a precipitate, formation of a gas, temperature change, odour change,
• state symbols

  (s)solid

  (l)liquid

  (g)gas

  (aq)aqueous (dissolved in water)
• How to name a compound

  1. The first name comes from the metal

  2. The second name comes from the non-metal

  2 elements: a metal and a non-metal (including oxygen).

  The second name will finish in ide.

  3 elements: a metal, a non-metal, plus

  oxygen

  The second name will usually finish in ate
• flame test colours

  Sodium- Yellow / orange

  Potassium- Lilac

  Lithium -Crimson

  Copper-Green/Blue

  Strontium-Red

  Calcium -Brick red

  Barium - Apple green
• Observations from flame tests can be used to identify the metals in compounds.
• Rusting occurs when iron reacts with oxygen AND water: iron + oxygen + water → iron(III) oxide
• Rusting can be prevented by keeping oxygen or water away from the iron

  For example by:

  ● storing the metal in an inert atmosphere such as argon

  ● Storing with a desiccant to absorbs water vapour

  ● Keeping water and oxygen away from the iron surface by creating a barrier e.g.

  by

  ○ Painting

  ○ oiling and greasing

  ○ coating with plastic
• Salts and acids speed up rusting.

  This is because they allow the oxidation reaction to happen faster.
• GROUP 1 METALS

  Group 1 is known as the ALKALI METALS.

  ● They are soft

  ● They are a shiny grey

  colour, but quickly tarnish (dull) when they react with oxygen.

  ● They react with water.

  ● The further down the group, the more reactive the metal is.

  
• Metal + Water → Metalhydroxide + Hydrogen
• Mg + H2O → Mg(OH)2 + H2
• Hydrochloric Acid-HCl

  Sulfuric Acid-H2SO4

  Nitric Acid-HNO3
• To test if a gas is hydrogen:

  A lit splint held to the mouth of a test tube of hydrogen gas will make a squeaky pop
• Acid + Metal → Salt + Hydrogen
• M-metal

  a-acid

  s-salt

  h-hydrogen
• A balanced equation is one in which there is the same number of each atom on each side (this is is because mass is being conserved).
• We need to use big numbers to change the equation:

  Mg(OH)2 + 2 HNO3 → Mg(NO3)2 + 2 H2O
• We can list metals in order of chemical reactivity.

  This depends on how they react with oxygen, water and acid.

  This is called the reactivity series.

  We can use the Reactivity Series to predict the reactions of metals.

  
• A more reactive metal will displace a less reactive metal from a compound in a displacement reaction.

  Copper sulfate + zinc → Zinc sulfate + copper

  Here, the zinc is more reactive than the copper, so the zinc displaces the copper in the displacement reaction.