Lewis Structures and Molecular Geometry

The video tutorial explains how to draw the Lewis structure for the SeO4 2- ion. It begins by counting the valence electrons of selenium and oxygen, including the extra electrons from the 2- charge. The tutorial then guides through placing selenium in the center and arranging oxygen atoms around it, forming bonds, and ensuring each atom satisfies the octet rule. The video addresses the issue of formal charges, showing how to adjust them to be as close to zero as possible while maintaining the overall charge of the ion. The final structure is enclosed in brackets to indicate its ionic nature, and the molecular geometry is noted as tetrahedral.

What is the total number of valence electrons in SeO4 2-?

• 34

• 32

• 30

• 28

Which element is placed at the center of the SeO4 2- Lewis structure?

• Carbon

• Selenium

• Sulfur

• Oxygen

How many oxygen atoms are arranged around the central selenium atom in SeO4 2-?

• Three

• Four

• Two

• Five

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

• To increase the atomic number

• To form a chemical bond

• To decrease the atomic mass

• To change the element

What is the octet rule in the context of Lewis structures?

• Atoms aim to have eight electrons in total

• Atoms aim to have eight valence electrons

• Atoms aim to have eight neutrons

• Atoms aim to have eight protons

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

• To increase the molecular weight

• To achieve a more stable structure

• To increase the number of atoms

• To change the molecular geometry

What is the formal charge on the central selenium atom after adjusting the Lewis structure?

• 0

• -2

• +1

• -1

What should be added to the Lewis structure to indicate that it is an ion?

• A triangle

• Brackets

• A square

• A circle

What is the molecular geometry of SeO4 2-?

• Trigonal planar

• Linear

• Bent

• Tetrahedral

What is the overall charge of the SeO4 2- ion?

• +1

• -2

• 0

• -1