Trigonal planar
SeO3-2 stands for Selinite Ion.
SeO3 would be acidic, tending to make selenic acid H2SeO4
The name of the compound SeO3 is selenium trioxide.
The Lewis structure of selenium trioxide (SeO3) has a trigonal planar geometric shape. This is due to the central selenium atom being bonded to three oxygen atoms with double bonds, resulting in a bond angle of approximately 120 degrees. The absence of lone pairs on the selenium atom contributes to this planar arrangement.
Sulfur tetraoxide is a trigonal planar. There is the sulfur in the middle and three oxygen that surrounds it with all of them a double bond linking them to the sulfur.
polar
trigonal planar
Lithium is Li^+ , and selenite is SeO3^2-. It will take 2 Li^+ for each SeO3^2-, so the formula is Li2SeO3
Fe2(SeO3)3
The hybridization of SeO3 is sp3, as selenium has four electron groups around it (three bonding pairs and one lone pair). This results in a tetrahedral arrangement of electron pairs and a sp3 hybridization.
There are two unbonded electrons present in SeO3^2-.
The chemical formula for diselenium dichloride is Se2Cl2.