Lewis Structures and Formal Charges

The video tutorial explains how to write the Lewis structure for the H2PO4- ion. It begins by counting the valence electrons for hydrogen, phosphorus, and oxygen, totaling 32 electrons. The structure is built with phosphorus in the center, surrounded by four oxygens, and hydrogens attached to two of the oxygens. The video then discusses completing the octets and checking formal charges to ensure the most stable structure. Adjustments are made by forming a double bond to optimize the formal charges, resulting in a more favorable Lewis structure.

How many total valence electrons are present in the H2PO4- ion?

• 30

• 32

• 34

• 36

Which element is placed at the center of the Lewis structure for H2PO4-?

• Nitrogen

• Phosphorus

• Oxygen

• Hydrogen

Why are hydrogens placed on the outside of the Lewis structure?

• They have the highest electronegativity.

• They are always placed on the outside.

• They form the most bonds.

• They are the heaviest atoms.

What is the purpose of placing electrons between atoms in a Lewis structure?

• To increase the atomic mass

• To form chemical bonds

• To decrease the charge

• To change the element

How many valence electrons do hydrogen atoms need to be stable?

• 1

• 2

• 3

• 4

What is the formal charge on the central phosphorus atom in the initial Lewis structure?

• +1

• 0

• +2

• -1

What adjustment can be made to improve the formal charges in the Lewis structure?

• Form a double bond

• Remove electrons

• Add more electrons

• Change the central atom

What should the formal charge on the oxygen atoms without hydrogens be after adjustment?

• +1

• 0

• -1

• -2

Why is it important to check formal charges in a Lewis structure?

• To increase the number of bonds

• To make the structure symmetrical

• To verify the structure's stability

• To ensure the structure is colorful

What is the overall charge of the H2PO4- ion?

• -2

• -1

• 0

• +1