Question

Draw the lewis dot structure for SeF3+. Also write the arrangement and geometry of the molecule.

Answer 1

Step 1: Find the Total Number of Valence Electrons.

In this step, add up the total number of valence electrons from all the atoms in the molecule.

Step 2: Find the Number of Electrons Needed to Make the Atoms "Happy".

An atom is considered "happy" if the atom's outer electron is filled. Elements up to period four on the periodic table need eight electrons to fill their outer electron shell. This property is often known as the "oclet rule ".

Step 3: Determine the number of bonds in the molecule.

Covalent bonds are formed when one electron from each atom forms an electron pair. Step 2 tells how many electrons are needed and Step 1 is how many electrons you have. Subtracting the number in Step 1 from the number in Step 2 gives you the number of electrons needed to complete the octets. Each bond formed requires 2 electrons, so the number of bonds is half the number of electrons needed, or:

(Step 2 - Step 1)/2

Step 4: Choose a Central Atom.

The central atom of a molecule is usually the least electronegative atom or the atom with the highest valence. To find electronegativity, either rely on periodic table trends or else consult a table that lists electronegativity values. Electronegativity decreases moving down a group on the periodic table and tends to increase moving from left to right across a period. Hydrogen and halogen atoms tend to appear on the outside of the molecule and are rarely the central atom.

Step 5: Draw a Skeletal Structure.

Connect the atoms to the central atom with a straight line representing a bond between the two atoms. The central atom can have up to four other atoms connected to it.

Step 6: Place Electrons Around Outside Atoms.

Complete the octets around each of the outer atoms. If there are not enough electrons to complete the octets, the skeletal structure from step 5 is incorrect. Try a different arrangement. Initially, this may require some trial an error. As you gain experience, it will become easier to predict skeletal structures.

Step 7: Place Remaining Electrons Around the Central Atom.

Complete the octet for the central atom with the remaining electrons. If there are any bonds left over from Step 3, create double bonds with lone pairs on outside atoms. A double bond is represented by two solid lines drawn between a pair of atoms. If there are more than eight electrons on the central atom and the atom is not one of the exception to the ocpet rule the number of valence atoms in Step 1 may have been counted incorrectly.