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Homework Help: Looking for someone to check my chem. questions.

  1. Nov 3, 2008 #1
    1Q. Explain why you would expect a BeF2 molecule to be linear but a SF2 molecule to be angular?

    A. Beryllium fluoride would be linear because each of the two valence electrons in a beryllium atom is shared with an electron from a fluorine atom. Using the valence electron-pair repulsion theory applied to two electron pairs, we would perdict that the angle between the fluorine atoms to be 180deg. The central atom uses all of its bonding electrons to bond to two identical atoms.
    SF2, when two atoms are bonded to a third, the resulting molecules are angular if unbonded outer electrons are present in the central atom. The two fluorine atoms would repel at a 109deg.

    2aQ. How would you designate the hybrid orbitals formed by "mixing" one d, one s, and two p orbitals?

    A. The hybrid orbitals formed would be dsp2.

    b) How many hybrid orbitals would be formed by the "mixing"?

    A. The number of hybrid orbitals formed would be 4. The total number of orbitals you put in are equal to the number of hybrid orbitals you get.

    3Q. Explain why C20H40 is a solid @ 25degcel, while C4H8 is a gas @ 25degcel?

    A. C20H40 is a larger compound having more atoms than C4H8 therefore having more electrons. The forces in C20H40 are a lot greater that C4H8 making C20H40 harder to break down resulting in a higher boiling point that C4H8.

    Am I on the right track here? Any help would be greatly appreciated.
  2. jcsd
  3. Nov 3, 2008 #2


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    Staff: Mentor

    Melting is not about breaking down, it is about intermolecular forces.

    For the first question think in terms of hybrydization.
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