Naming Chemical Compounds - Weebly



Writing the Chemical Formula

(When given the name of the compound)

1. Look at the name. The metal is always the first part of the name (unless a compound is made up of two non-metals). Write the symbol of the metal. If you see prefixes in the name (this would happen when you have two non-metals bonded together or a metalloid in the compound), skip to step #6.

2. Determine the charge on the metal. If the element is from groups IA, IIA, or IIIA it will have a charge of +1, +2, or +3, respectively. If the element is a transition metal, the Roman numeral will tell you the charge.

3. Write the symbol for the non-metal.

If the name ends in -ide, it is one type of element and it can be found on the periodic table..

If the name ends in -ate or -ite, (or has the name “hydroxide” or “cyanide”) it is a polyatomic ion...look it up on the ion chart on the back of your periodic table.

4. Determine the charge on the non-metal. If the element is from groups VA, VIA, or VIIA it will have a charge of 3-, 2-, or 1-, respectively. If the non-metal is a polyatomic ion, the charge is always the same - look it up on your sheet.

5. Balance the charges so that your "pluses" balance your "minuses." Use subscripts to balance the charges. If you have more than one polyatomic ion, enclose it in parentheses! Be careful – people often forget to put parentheses around “OH.”

6. If you see prefixes in your name (mono-, di-, tri-, etc.) then simply use the prefix to determine how many of each element there is! No need to worry about charges here!

Examples:

Calcium bromide Iron (III) carbonate

Magnesium phosphate Manganese (IV) oxide

Lead (II) phosphate Ammonium sulfide

Aluminum nitrate Copper (II) hydroxide

Sulfur trioxide Dinitrogen pentoxide

Naming Chemical Compounds

(When given the chemical formula)

Most compounds are composed of a metal and a non-metal. When naming compounds, the metal is always named first and the non-metal is always named second.

1. If you have an ionic compound, determine which element in your compound is the metal and which is the non-metal (remember, you may have polyatomic ions that you will have to look up on your sheet). If you have a covalent compound (two non-metals combined together), skip to step #3.

2. How to write the name:

If the metal is…

If the non-metal is….

3. If the compound is composed of two non-metals or has a metalloid in it, name the compound using prefixes to tell how many there are of each "part." The second non-metal always has an -ide ending. (Use these prefixes: 1-mono, 2-di, 3-tri, 4-tetra, 5-penta, 6-hexa, 7-hepta, 8-octa, 9-nona). (The prefix mono is only used in a name if there is one atom of the second non-metal only). Don’t do anything with the charges!

Examples:

CaCl2 MgSO4

LiNO3 CO2

N2O5 Cr2O3

Ca(ClO3)2 FeO

Cu2SO4 Ti3(PO4)2

SO AgBr

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A transition metal (in the “d” block)

From Family IA, IIA or IIIA

Bismuth, Cadmium, Lead, Silver, Tin or Zinc – it’s strange!

Write the name of the metal followed by the charge of it as a Roman numeral – Determine what the Roman numeral is using the nonmetal portion of the compound that you know the charge of! Remember – all compounds are neutral, so positive and negative charges have to balance!

Bismuth, Tin and Lead need roman numerals

Cadmium, Silver and Zinc do not need roman numerals! Silver is always +1; Cd and Zn are always +2!

Just write the metal’s name

More than one type of element (PO4 or OH, for example)

Only one type of element

(Br or Cl2, for example)

Find the polyatomic ion on your sheet and simply write the name of it

Write the name with an “-ide” ending

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