Chemistry

View mindmap
  • Periodic Table
    • Mendeleve:
      • Arranged elements in order of increasing mass & He left gaps for undiscovered elements.
    • Today
      • Arranged in order if increasing atomic number
        • 18 groups & 7 periods
    • Periodicity
      • it refers to any repeating trends that are seen in the elements properties (in a period)
        • Periodic Properties include Ionisation Energies, Electronegativity, Atomic Radius
      • Ionisation Energies
        • It is the energy required to remove one electron from one mol of gaseous atoms to form one mol of gaseous 1+ atoms
          • Strong IE- strong attraction between nucleus& outer shell so more energy is required to overcome attraction & remove the electron
        • Strong IE- strong attraction between nucleus& outer shell so more energy is required to overcome attraction & remove the electron
        • Increases across a period due to more protons which means a higher nuclear charge so stronger attraction between outer electron & shell so more energy required
        • Decreases down a group because increased electrons means increased shell number so shielding gets in the way and outer electrons are further from the nucleus so there is a weaker attraction so less IE id required
        • EXCEPTIONS
          • The drop between group 2&3 is due to sub shell structure
            • In group 2 the outer electron is in an s-orbital whereas in group 3 the outer electron is in a p-orbital. Even though a p-orbital has slightly higher energy than an s-orbital, a p-orbital has shielding from the nucleus and so on average the p-orbital electron is found further from the nucleus hence the drop in IE
          • The drop between group 5&6 is due to P-orbital repulsion
            • In group 5 the electron is being removed from a single occupied p-orbital whereas in group 6 it is being removed from a shared orbital. The repulsion between the 2 electrons makes it easier to remove the electron from a shared orbital hence the drop in IE
        • You can use IE to predidc no of electrons in the outer shell, The group of the element or the identity of an element
    • Group 7 Elements
      • They exist as Diatomic molecules
      • Each halogen has 7 electrons in their outer shell so are very reactive
        • Halogens are OXIDISING AGENTS- It oxidises another species whilst itself gets reduced
          • Fluorine is so reactive it is rarely found in its natural state
          • Astatine is so radioactive its never found in its natural form
      • A more reactive halogen will displace a less reactive halogen in a solution and when it reacts it forms a precipitate of the less reactive halogen
      • To test which Halide ion is in solution: Add DILUTE NITRIC ACID to mystery solution then add SILVER NITRATE and a precipitate will form
        • Chlorine = White, Bromine = Cream and Iodine = Yellow
          • Then add DILUTE AMMONIA SOLUTION and if it dissolves it is a chloride
            • Then add CONCENTRATED AMMONIA SOLUTION  and if it dissolves its a bromine and if it remains its an iodide
      • They DISPROPORTINATE
        • CHLORINE +( cold aqueous )NaOH = Sodium Chlorate(1) Solution = BLEACH
        • Chlorine + Water = HCl + HClO( chloric(I) Acid
          • HClO + Water = chlorate(I) ions (ClO-)(hypochlorite ions) + H3O-
    • Group 2 Elements
      • It has 2 electrons in its outer shell
        • REDOX reactions are most common
          • Group 2 Elements
            • It has 2 electrons in its outer shell
              • REDOX reactions are most common
                • Redox with OXYGEN to form METAL OXIDE
                • Redox With WATER to form ALKALINE HYDROXIDE
                • Redox with DILUTE ACID to form a SALT & HYDROGEN GAS
            • It is a REDUCING AGENT - It reduces another species whilst itself gets  oxidised
            • Trends: As you go down the group (IE decreases, atomic radius increases and shielding increases so)They get MORE REACTIVE   and STRONGER REDUCING  agents
            • Uses
              • Agricultural- CaOH is added to neutralise acidic soil
              • Bases- G2 Carbonates, Oxides and Hydroxides have many uses as bases due to  properties
              • G2 Bases  are used as Antacids to neutralise HCl stomach acid- Many tablets contain MgOH , CaCO , & MgCO
          • Redox with OXYGEN to form METAL OXIDE
          • Redox With WATER to form ALKALINE HYDROXIDE
          • Redox with DILUTE ACID to form a SALT & HYDROGEN GAS
      • It is a REDUCING AGENT - It reduces another species whilst itself gets  oxidised
      • Trends: As you go down the group (IE decreases, atomic radius increases and shielding increases so)They get MORE REACTIVE   and STRONGER REDUCING  agents
      • Uses
        • Agricultural- CaOH is added to neutralise acidic soil
        • Bases- G2 Carbonates, Oxides and Hydroxides have many uses as bases due to  properties
        • G2 Bases  are used as Antacids to neutralise HCl stomach acid- Many tablets contain MgOH , CaCO , & MgCO
  • Add one spatula of each G2 METL OXIDE to Water in a test tube, SHAKE the mixture ( there isn't enough water to dissolve all of the metal oxide so a WHITE PRECIPITATE forms), Measure the pH of the sample, ALKALINITY INCREASES DOWN A GROUP
    • Solubility test

    Comments

    No comments have yet been made

    Similar Chemistry resources:

    See all Chemistry resources »See all Periodic table and its trends resources »