IB DP Chemistry: HL复习笔记9.1.4 Naming Transition Metal Compounds

• Transition metals are characterized by having variable oxidation numbers.
• Oxidation numbers can be used in the names of compounds to indicate which oxidation number a particular element in the compound is in
• Where the element has a variable oxidation number, the number is written afterwards in Roman numerals.
• This is called the STOCK NOTATION (after the German inorganic chemist Alfred Stock), but is not widely used for non-metals, so SO₂ is sulphur dioxide rather than sulphur(IV) oxide
• For example, iron can be both +2 and +3 so Roman numerals are used to distinguish between them
  • Fe²⁺ in FeO can be written as iron(II) oxide
  • Fe³⁺ in Fe₂O₃ can be written as iron(III) oxide

Answer:

Answer 1: copper(I) oxide:

The ox. no. of 1 O atom is -2 and Cu₂O has overall no charge so the ox. no. of Cu is +1

Answer 2: manganese(II) sulfate:

The charge on the sulfate ion is -2, so the charge on Mn and ox. no. is +2

Answer 3: sodium chromate(VI):

The ox. no. of 2 Na atoms is +2 so CrO₄ has an overall -2 charge, so the ox. no. of Cr is +6

Answer 4: potassium manganate(VII):

The ox. no. of a K atom is +1 so MnO₄ has overall -1 charge, so the ox. no. of Mn is +7

Answer 5: sodium dichromate(VI):

The ox. no. of 2 Na atoms is +2 so Cr₂O₇ has an overall -2 charge, so the ox. no. of Cr is +6. To distinguish it from CrO₄ we use the prefix di in front of the anion