[VISUAL] Some binary compounds that form between fluorine and various nonmetals are listed in the ta — Bonding Chemistry Question
Problem Context
[VISUAL]
Some binary compounds that form between fluorine and various nonmetals are listed in the table above. A student examines the data in the table and poses the following hypothesis: the number of F atoms that will bond to a nonmetal is always equal to 8 minus the number of valence electrons in the nonmetal atom.
Model Answer
ClF
1 point is earned for the correct formula.
Model Answer
1 point is earned for a central Cl atom surrounded by three bonding pairs with F atoms and two nonbonding (lone) pairs of electrons. F atoms must have three nonbonding pairs each. Electron pairs can be depicted as dots or line segments.
Model Answer
The molecule is T-shaped because a T-shaped structure is asymmetric with dipoles that do not cancel out, but produce a net dipole (i.e., a polar molecule).
OR
because, if the molecule had a trigonal planar structure, the molecule would be symmetric with dipoles that cancel out and produce a net dipole of zero (i.e., a nonpolar molecule), which is not consistent with the observation that the ClF3 molecule does have a dipole moment.
1 point is earned for indicating that the molecule is T-shaped with an acceptable explanation.
Model Answer
An acceptable hypothesis (descriptive or formulaic) must include the following ideas:
1. Atomic Structure: e.g., odd number of F atoms
2. Periodicity: e.g., as the atomic number of the central halogen atom increases, the number of F atoms increases.
1 point is earned for an acceptably modified hypothesis that addresses both atomic structure and periodicity.