C4: The Periodic Table

C4: The Periodic Table

1. C4f: Transition Elements

   • Copper compounds are blue
   • iron (ll) compounds are light green
   • iron(lll) compounds are orange brown
   • Thermal decompostion
     • is a reaction where a substance is broken down into two or more substances by heating
     • When transition metal carbonates are heated a colour change happens
       • They decompose to form a metal oxide and carbon dioxide
     • copper(ll) carbonate = copper(ll) oxide + carbon dioxide
     • CuCO3 = CuO + CO2
   • Precipatation
     • Is the reaction between solutions that makes an insoluble solid
       • The insoluble solid is known as a Precipitate
     • Copper(ll) = Blue
     • Cu2+ + 2OH- = Cu(OH)2
   • Lime water = milky CO2

2. C4e: The Group 7 Elements

   • Chlorine
     • Green gas at room Temperature
     • Uses: To sterilise water, make pesticides and plastics
   • Bromine
     • Orange solid at room temperature
   • Iodine
     • Grey solid at room temperture
     • Used as an antiseptic
   • Halogens react vigorously with alkali metals to form halides
     • Lithium + Chlorine = Lithium Chloride
     • 2Li (s) + Cl (g) = 2LiCl (s)
   • Displacement Reactions
     • Chlorine will displace bromides and iodides
     • Bromine will displace iodides
     • Potassium bromide + chlorine = potassium chloride + bromine
     • 2KBr + Cl2 = 2KCl + Br2
   • Group 7 atoms gain one electron to form a negative ion with a stable structure
     • Reduction is the reaction that takes place: eg
       • F2 + 2e- = 2f-

3. C4d: The Group 1 Elements

   • These are all Alkali Metals
   • They have to be stored under Oil because they:
     • React with Air
     • React Vigourously with water
   • Alkali Metals react with a metal to produce a hydrogen and a hydroxide
     • 2Li (s) + 2H2O (l) =2LiOH (aq) + H2 (g)
   • Lithium reacts gently, Sodium reacts more violently, Potassium reacts even more violently
   • Flame Tests
     • 1. A piece of nichrome wire is dipped in water
     • 2. The wire is dipped in a solid compound then put into a Bunsen flame
     • 3. Each compound will produce a different coloured flame
     • Lithium = red
     • Sodium = Yellow
     • Potassium = Lilac
   • Group 1 metals all lose one electron so a positive ion is made
     • Oxidation is the reaction that takes place: eg
       • Li = Li+ + e-

4. C4c: The Periodic table & Covalent Bonding

   • Groups are columns
   • Periods are rows
   • The electronic structure is 2.8.8.2
   • 3 Types of Bonding
     • Metallic = metals only
     • Ionic = Metals and non metals
     • Covalent = non metals
   • Covalent Bonding
     • Non metals sharing electrons
     • Water
       • Is liquid at room temperature
       • low melting point
     • Carbon Dioxide
       • Gas at room temperature
       • low melting point
     • Simple bonded molecules have low melting points because they have weak intermolecular forces
     • No conducted electricity because there are no free electrons
   • Molecules
     • Hydrogen = two hydrogen atoms share a pair of electrons
     • Methane= carbon atom shares a pair of electrons with 4 hydrogen atoms
   • Mendeleev made the periodic table - but left gaps for unknown elements

5. C4b: Ionic Bonding

   • Ion is a charged atom
   • Positive ion is made when an atom loses an electron
   • Negative ion is when an atom gains an electron
   • Ionic Bonding
     • 1. metal atom loses all outer shell electrons to become a positive ion
     • 2. non-metal atom gains electrons to fill its outer shell and become a negative ion
     • 3. positive and negative ions are attracted to each other (ionic bond)
   • Structure
     • Giant ionic lattices
     • Positive and negative ions strongly attracted to each other
   • Properties
     • High melting points
     • can conduct electricity when molten
     • can't conduct electricity when solid
   • Ions with different charges make ion compounds which have equal amounts of positive an d negative charge

6. C4a: Atomic Structure

   • Structure
     • Electron (-1) around the nucleus
     • Protons (+1) in the nucleus
     • Neutrons (0) in the nucleus
   • Mass Number = total protons and neutrons
   • Atomic Number = total protons
   • Isotopes
     • Atoms of the same element same atomic number but different mass number
     • Different number of neutrons
     • Same number of protons and electrons
   • Electronic configuration
     • 2.8.8.2

7. C4h: Purifying and Testing Water

   • Uses of Water
     • Coolent
     • Solvent
     • Raw material
   • Water treatment
     • 1. Sedimentation - the insoluble particles sink
     • 2. Filtration to remove fine particles
     • 3. Chlorination - to kill microorganisms
     • Tap water isn't pure - it must be distilled but that is expensive and uses a lot of energy
   • Pollutants in water
     • Nitrates from run off fertilisers
     • Lead compounds from old pipes in the plumbing
     • Pesticides from spraying crops near water supplis
   • Dissolved Ions
     • Silver nitrate used to detect halide ions
       • Bromides = cream precipitate
         • Sodium sulfate + barium chloride = barium sulfate + sodium chloride
         • Na2SO4 + BaCl2 = BaSO4 + 2NaCl
       • Iodides = pale yellow precipitate
       • Chlorides = white precipitate

8. C4g: Metal Structure and properties

   • Transitional Metals
     • Iron is used to make steel
     • Copper is used to make electrical wiring
     • Lustrous: Jewellery
     • Hard + High Density: Drill Bits
     • High Tensile Strength: Bridges
     • Conducters of heat + electricity
   • Structure
     • High melting points
     • High boiling points
       • Lots of energy needed to break bonds
     • Positive metal ions in a sea of delocalised electrons
     • Held together by metallic bonds
   • Superconductors
     • Metals are able to conduct electricity because electrons flow easily through them
     • At -200 degrees some metals can become superconductors
     • It has no resistant to the flow of electricity
     • Used for:
       • Powerful elctromagnets
       • Very fast electronic circuits
       • Power transmission that doesn't lose energy
     • Costly to maintain temperture

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