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    Density and Melting Point

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    Questions on density:
    1. Using the table below determine any trends of density that might be related to the periodic table.
    Substance Density (g/L) Substance Density (g/L)
    H2 0.0899 O2 1.429
    He 0.1785 N2 1.2506
    Ne 0.9 Cl2 3.214
    Ar 1.7825 Kr 3.75
    F2 1.696 Xe 5.9

    2. In the early days of the periodic table, the 1870s, both silicon and tin were known elements, but germanium was unknown. Using these trends and the densities of silicon and tin that you just obtained, estimate the density of germanium?

    3. Melting Point
    Halogen Melting point
    F2 54 K
    Cl2 172 K
    Br2 266 K
    I2 387 K

    a. Graph the data above, put the melting point on the y-axis and atomic number on the x-axis

    b. What trends if any do you notice from the data regarding melting point and the periodic table?

    c. What is the predicted melting point of astatine? How did you determine the melting point? (Hint - use your graph)

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    Solution Preview

    1. The trend of density in the periodic table can be determined by looking at the atomic numbers - the higher the atomic number, the denser the atom.Among gaseous and liquid nonmetals, as atomic number increases, London dispersion forces increase with the number of electrons, resulting in higher polarity and intermolecular attraction. Therefore, density generally increases as atomic number increases.

    The majority of metals have higher densities than the majority of nonmetals. The ...

    Solution Summary

    Density and melting points are provided for substances. The early periodic table is provided.