Understanding Chromium Ions and Oxidation Numbers

The video tutorial explains the concept of the chromium 3 ion, highlighting its positive charge as a cation due to the loss of three electrons. It further delves into the concept of ionic charge, emphasizing that the oxidation number for such ions is determined by the total charge. The oxidation number for the chromium 3 ion is identified as plus 3, with a note on the notation difference between ionic charge and oxidation number. The tutorial concludes with a summary of these key points.

What does the '3 plus' in Cr3+ indicate about the chromium ion?

• It has a neutral charge.

• It has gained 3 protons.

• It has lost 3 electrons.

• It has gained 3 electrons.

How is the ionic charge of an ion like Cr3+ determined?

• By the number of protons in the nucleus.

• By the number of neutrons in the nucleus.

• By the number of electrons lost or gained.

• By the atomic mass of the element.

What is the oxidation number of the chromium 3 ion?

• 0

• -3

• +3

• +1

In the context of oxidation numbers, where is the plus sign placed?

• After the number

• Before the number

• It is not used

• At the end of the formula

What do all oxidation numbers for an ion add up to?

• The charge on the ion

• The atomic number

• The number of protons

• The mass number