Simplify the following text for a Grade 10 native English-speaking person.
Original: Manganese forms chemical compounds in several oxidation states : +2 , +4 , and +7 are the most common .
Simplified: The most common oxidation states of manganese are +2 , +3 , +4 , +6 and +7 , though oxidation states from â ' 3 to +7 are observed .