# How do you draw the Lewis structure for #SeO_2#. What is the electron geometry around the central atom?

##### 1 Answer

**WARNING!** Long answer.

#### Explanation:

Here are the steps I follow when drawing a Lewis structure.

**1.** Decide which is the central atom in the structure.

That will normally be the least electronegative atom (

**2.** Draw a skeleton structure in which the other atoms are single-bonded to the central atom:

**3.** Draw a trial structure by putting electron pairs around every atom until each gets an octet.

In this editor, I will have to write it as

**4.** Count the valence electrons in your trial structure (20).

**5.** Now count the valence electrons you actually have available.

The trial structure has two extra electrons.

**6.** Draw a new trial structure, this time inserting one double bond for each extra pair of electrons:

**7.** As before, add valence electrons to give each atom an octet:

and

**8.** Calculate the formal charge on each atom.

and

**9.** We see that some of the atoms have formal charges.

The “best” Lewis structure is one in which has the fewest formal charges.

We can generate a structure with zero formal charges if we move a lone pair from the single-bonded

This gives us a third possibility:

We now have a structure in which

However, that’s OK, because

We have three different structures, differing ONLY in the locations of the electrons.

We say that these are **resonance structures** of

The actual structure of **resonance hybrid** of all three structures.

In all three structures, there are three electron domains about the

The electron geometry around **trigonal planar**.