Question

1). What is the Lewis structure for `"SeF"_4`? 2). What is its electron geometry? 3). What is its molecular geometry? 4. What is its hybridization? 5. How would you classify it in the `"AXE"` system? 6. What are the ideal bond angles?

Answer 1

1) See below; 2) trigonal bipyramidal; 3) see-saw; 4) sp³d; 5) AX₄E; 6) see below.

Explanation:

1) 1 Se + 4 Br = 6 + 4×7 = 34 valence electrons. Se must expand its octet. This gives Se four bond pairs and one lone pair. The Lewis structure is like that of SeF₄.

2). The electron arrangement for five electron pairs is trigonal bipyramidal.

3) The bulky lone pair occupies an equatorial position.

The molecular shape considers only the Se-Br bonds. As with SF₄, the shape is a see-saw.

4) The hybridization that corresponds to five electron pairs is sp³d.

5) The VSEPR notation is AX₄E.

6) The bond angles are:
axial-axial = > 180°;
equatorial-equatorial = < 120°;
axial-equatorial = < 90°.

You can watch a video on trigonal bipyramidal geometry here: