Chemical Bonding: AsF₆^- Lewis Structure

Drawing the Lewis Structure for AsF₆^-

Viewing Notes:

• With AsF₆^- be sure to add an additional valence electron to your total because of the negative sign.
• There are a total of 48 valence electrons in AsF₆^-.
• Arsenic (As) is the least electronegative and goes at the center of the Lewis structure.
• Arsenic (As) is in Period Four on the periodic table and can hold more than 8 valence electrons.
• Be sure to put brackets and a negative sign around the AsF₆^- Lewis structure to show that it is an ion.

Transcript: This is the Lewis structure for AsF6-. Arsenic has 5 valence electrons and Fluorine has 7, but we have 6 Fluorines and this negative up here means we have an additional valence electron. Five plus 42 plus 1 equals 48 total valence electrons for the AsF6- Lewis structure. Arsenic is the least electronegative, we'll put that at the center and then we'll put the 6 Fluorines around the outside.

We'll form single bonds between the Arsenic and the Fluorines, two valence electrons in each bond. Then we'll go around the outside to fill the octets for the Fluorine. So we've used 2, 4, 6, 8, 10, 12 valence electrons; 14, 16, and 48. So we've used all the valence electrons, all 48 we started out with for AsF6-. All the Fluorines have octets. The Arsenic has more than 8 valence electrons, but that's OK: it's in period 4 of the periodic table, so it can hold more than 8.

And if you check the formal charges for each atom in the AsF6- Lewis structure, you'll see that they are 0. And this is the Lewis structure for AsF6-, Hexafluoroarsinate ion. One last thing we do need to do, though, is add brackets around this to show that it's an ion.

This is Dr. B., and thanks for watching.