SCH 3U - Nomenclature - Ous/Ic Naming System

A third, and least commonly used method of naming compounds, in which the first element may have more than one valence is called the ‘ous-ic’ system.  This system makes use of the Latin names of many of the metals.

copper ⇉ cuprum

iron ⇉ ferrum

lead ⇉ plumbum

tin ⇉ stannum

gold ⇉ aurum

Rules for Writing a Name from a Formula

1.     Write the name for the first element.  Remove the ending and add either ‘-ous’ (if the element is using its lower valence) or ‘-ic’ (if the element is using its higher valence).

2.    Write the name of the second element.  Remove the ending and add ‘-ide’.

ex.(a)  PbBr₂     plumbous bromide

     (b)  PbBr₄     plumbic bromide

              

Rules for Writing a Formula from a Name

1.     Write down symbols for the two elements, in the order they appear in the name.

2.    Place the valence of the first element above the first symbol (‘-ous’ = lower valence, ‘-ic’ = higher valence).

3.    Place the valence of the second element above the second symbol.

4.    Use the ‘criss-cross’ rule and write the numbers as subscripts.

5.    Reduce the subscript numbers to the simplest ratio.

ex.(a)  stannous chloride       Sn²   Cl¹ ↝  SnCl₂

     (b)  stannic chloride          Sn⁴   Cl¹ ↝  SnCl₄

Can I get an "ous"?  Can I get an "ic"?  Can I get a video?

_Homework

 

Give the correct formula for the following.

1.     mercuric oxide

2.    cupric iodide

3.    stannous chloride

4.    ferric chloride

5.    arsenious sulfide

6.    plumbic fluoride

7.    nickelic oxide

8.    phosphorous chloride

9.    antimonic oxide

10.  carbonic oxide

11.  manganous sulfide

12.  arsenic oxide

13.  stannic iodide

14.  cuprous chloride

15.  auric oxide

16.  chromic iodide

17.  aurous bromide

18.  ferrous sulfide

19.  sulfuric oxide

20. sulfurous oxide

Give the correct name for the following.

1.     CO₂

2.    Sb₂O₅

3.    PCl₃

4.    Ni₂O₃

5.    PbF₄

6.    As₂S₃

7.    FeN

8.    SnCl₂

9.    CuI₂

10.  HgO

11.  SO₂

12.  SO₃

13.  FeS

14.  AuBr

15.  CrI₃

16.  Au₂O₃

17.  SnI₄

18.  MnS

19.  As₂O₅

20. CuCl₂

 

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