The possible molecular geometries are:
Step 1: Iodine (EN = 2.66) is less electronegative than Fluorine (EN = 3.98) iodine is the central atom.
Step 2: The total number of valence electrons present in IF3 is:
Group Valence Electrons
I 7A 1 × 7 e– = 7 e–
F 7A 3 × 7 e– = 21 e–
Total: 28 valence e–
Step 3: I will go in the center while F atoms are terminal atoms (Recall that when halogens are not the central atom, they only form 1 bond.).
Let’s first connect each atom with single bonds.
A bond corresponds to 2 electrons shared between two atoms so we currently have 3 × 2 e– = 6 val. e–, which means we’re still lacking 22 e–. We can start adding the missing electrons to each atom while following the octet rule.
The complete Lewis structure is:
I has 10 e–(exemption to the octet rule), and F: 8 e– each
Step 4: The shape of a molecule is based on its molecular geometry: when determining molecular geometry, atoms and lone pairs are treated differently.
Predict the molecular geometries of the following species, respectively: IF3, TeF4, XeF51+.
A. trigonal pyramidal, square planar, linear
B. trigonal pyramidal, tetrahedral, see-saw
C. trigonal planar, tetrahedral, square pyramidal
D. T-shaped, see-saw, square pyramidal
E. trigonal planar, see-saw, square planar
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