C2 mindmap

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  • C2
    • development of the periodic table
      • the periodic table was formed as chemists classified elements
        • named the periodic table because of the regularly repeating patterns in the properties of all the elements
          • mendeleev's periodic table had gaps for unknown elements
    • electronic structures  and periodic table
      • atomic number (proton) determines position
        • no. of electrons in outer shell determines chemical properties.
          • number of electrons in OS equals group number
            • atoms of metals tend to lose electrons whereas those of non metals gain
          • (and reactivity)
    • group 1 - the alkali metals
      • melting and boiling points decrease going down the group
        • all react with water to produce hydrogen and an alkaline solution containing the metal hydroxide
          • form positive ions charge +1 in reactions to make ionic compounds
        • reactivity increases going down group
    • group 7 - the halogens
      • all form ions with a single negative charge in their ionic compounds
        • form covalent compounds by sharing electrons with other non-metals
        • more reactive halogens can displace a less reactive halogen from solution of one of its salts
          • reactivity of the halogens decrease going down the group
    • explaining trends
      • you can explain trends in reactivity as you go down a group in terms of attractuons between outer shell electrons and nucleus
        • this depends on:
          • distance between electrons and nucleus
            • no. of occupied inner shells
              • size of + charge on nucleus
          • these factors must be taken into account in deciding how easy it is for atoms to gain/lose electrons.
            • the increased nuclear charge, due to extra protons, going down a group is outweighed by the 2 other factors
              • therefore electrons are easier for larger atoms to lose and harder to gain going down a group
    • the transition elements
      • compared with alkali metals, transition elements have higher melting &boiling points.
        • stronger, harder & less reactive
        • do not react vigorously with oxygen or water
        • transition element can form ions with different charges
          • inportant industrial catalysts


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