Naming Binary Compounds Part II

The Stock System

Objectives

Name simple binary compounds using their formulae.

Given the name, write the formula of a simple binary compounds

The Stock System

The Stock System is used when the cation or the first part of the compound has more than one possible charge.

The charge of the cation/metal is denoted by a Roman Numeral.

Roman Numerals

1 = I

2 = II

3 = III

4 = IV

5 = V

6 = VI

7 = VII

8 =VIII

You will never use 8 and very seldom numbers over 4.

Special Case: Hg+1

Hg+1 is never by itself.

When you see it in a formula it will look like Hg2 and have a +2 charge

Example: Hg2Cl2 is mercury(I) chloride

However, Hg+2 is mercury(II)

Example HgCl2 is mercury(II) chloride

Examples

Iron has 2 possible charges Fe+2 & Fe+3

They would be Fe (II) or Fe (III)

Ions/metals that only have one charge there is no reason to use the Roman Numerals

Examples

Fe2O3 and FeO

In Fe2O3 the Iron has a +3 charge so the name would be: Iron (III) Oxide

In FeO the Iron has a +2 charge so the name would be: Iron (II) Oxide

Try It Your Self

Step I: Determine the charge on the metals using the non metal part (ex. O and Cl)

Step II: Write the correct name.

Here are your problems: CuO and CuCl

Now pause the video and try them.

Answers

Copper (II) Oxide

Copper (I) Oxide

Next Up Naming Non-Metal Binary Compounds

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