C3 1 - The periodic table

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  • Created on: 11-03-13 19:07
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  • C3 1 - The periodic table
    • The early periodic table
      • Newlands, and then Mendeleev, attempted to classify the elements by arranging them in order of their atomic weights.
        • The elements can be arranged in a table so that elements with similar properties are in columns, known as groups.
      • The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
        • Mendeleev overcame some of the problems by leaving gaps for elements that he thought  had not been discovered.
      • It is called a periodic table because similar properties occur at regular intervals.
    • The modern periodic table
      • When electrons, protons and neutrons were discovered early in the 20th century, the periodic table was arranged in order of atomic numbers.
        • When this was done, all elements were placed in appropriate groups.
      • The modern periodic table can be seen as an arrangement of the elements in terms of their electronic structures.
        • Elements in the same group have the same number of electrons in the highest occupied energy level.
    • Group 1 elements (the alkali metals)
      • Metals with low density.
        • The first three can float on water.
      • React with non-metals to form ionic compounds.
        • The metal ion carries a charge of +1.
        • The compounds are white solids that dissolve in water to form colourless solutions.
      • React with water, releasing hydrogen.
      • Form hydroxides that dissolve in water to give alkaline solutions.
      • The further down a group an element is...
        • The more reactive the element is.
        • The lower its melting and boiling point.
    • Transition metals
      • Compared to the elements in group 1...
        • Have higher melting points (except for mercury)
        • Have higher densities.
        • Are stronger and harder.
        • Are much less reactive and so do not react as vigorously with water or oxygen.
      • Have ions with different charges.
      • Form coloured compounds
      • Are useful as catalysts.
    • Group 7 - the halogens
      • React with metals to form ionic compounds in which the halide ion carries a charge of -1.
      • The further down an element is...
        • The less reactive the element.
        • The higher its melting and boiling points.
      • A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt.
    • Trends within the periodic table
      • The higher the energy level of the outer electrons...
        • The more easily electrons are lost.
        • The less easily electrons are gained.


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