Oxidation Numbers and Elements

The video tutorial explains the concept of oxidation numbers, focusing on how they indicate where electrons spend more time based on electronegativity differences. It highlights that free elements like Br2 have an oxidation number of zero due to no electronegativity difference. The tutorial also covers how oxidation numbers change in compounds, using HBr as an example, where hydrogen has a +1 oxidation number and bromine has a -1 oxidation number, balancing to zero.

What do oxidation numbers indicate about an atom in a molecule?

• Where the electron is spending more time

• The atomic mass of the atom

• The number of neutrons in the atom

• The number of protons in the atom

Why do free elements like Br2 have an oxidation number of zero?

• Because they have a high atomic mass

• Because they are metals

• Because there is no difference in electronegativity between the atoms

• Because they are in a gaseous state

Which of the following is NOT a free element with an oxidation number of zero?

• H2

• HBr

• Br2

• O2

In the compound HBr, what is the oxidation number of hydrogen?

• +2

• 0

• +1

• -1

What is the oxidation number of bromine in HBr?

• -1

• 0

• +1

• -2

Which group does bromine belong to, and what is its typical oxidation number in compounds?

• Group 17, -1

• Group 18, 0

• Group 1, +1

• Group 16, -2

What is the oxidation number of bromine in Br2?

• -2

• 0

• +1

• -1