Mastering Oxidation Numbers in Compounds and Ions

This video tutorial covers the rules for assigning oxidation numbers to elements in compounds and ions. It begins with an introduction to the importance of understanding oxidation numbers in chemistry. The video then explains several rules, including how oxidation numbers in neutral compounds add up to zero, how they relate to ionic charges in ions, and specific rules for free elements, fluorine, peroxides, hydrogen, and oxygen exceptions. The tutorial concludes with a summary and encourages further practice to solidify understanding.

What is the sum of oxidation numbers in a neutral compound?

• It is always positive.

• It is always zero.

• It is always negative.

• It equals the charge of the compound.

In the sulfate ion (SO4^2-), what is the oxidation number of sulfur?

• -2

• +6

• +4

• 0

How do oxidation numbers differ from ionic charges?

• They are always the same.

• Oxidation numbers are always positive.

• They can differ; oxidation numbers can vary while ionic charges are fixed.

• Ionic charges are always zero.

What is the oxidation number of a free element?

• It is equal to the atomic number.

• It is always zero.

• It is equal to the number of protons.

• It is always negative.

What is the oxidation number of fluorine in compounds?

• -1

• 0

• +2

• +1

What is the oxidation number for elements in Group 1 of the periodic table?

• 0

• +1

• -1

• +2

In which compound does oxygen have an oxidation number of -1?

• H2O

• CO2

• Na2O2

• O2

What is the oxidation number of hydrogen when bonded to metals?

• +2

• 0

• -1

• +1

Which of the following is an exception to the rule that oxygen has an oxidation number of -2?

• CO2

• H2O

• O2

• OF2

What is the oxidation number of chlorine in ClO3^-?

• +3

• 0

• +5

• -1