Naming Chemical Compounds

I Know Who You Are

To Name a Chemical Compound Means You Ask the Following Questions

Is the compound ionic or covalent? Is the ionic compound an acid or not? Is the non-acidic ionic compound binary or

polyatomic? Rules for

– Ionic binary - Ionic polyatomic– Acids - Covalent

How do you know if it’s ionic or covalent?

The periodic table can be divided into two portions: metals and non-metals

Metals to the left; non-metals to right

Ionic compounds have metals and non-metals

Covalent compounds have only non-metals

Ionics have positive and negative ions

If it is ionic- has a metal and a non-metal- is it binary or polyatomic?

Binary ionic compounds contain only two different kinds of elements- one metal and one non-metal

– Examples: NaCl, KI, AlBr3, Cr2O3

Polyatomic ionic compounds contain three or more kinds of elements- usually one metal and a group of non-metals

– Examples: Na2SO4, (NH4)3PO4, KClO3

The method of naming is similar with subtle differences

Soooooo….what’s an acid?

Acids are a category of chemicals that have a certain set of chemical properties– pH < 7– Corrosive– Reacts with metal– Sour taste– Produce H+1 when dissolved in water

We’ll identify them as ionic compounds containing an H+1 ion as the metal

Naming Flow Chart

Is the compound ionic or covalent?

Ionic: Is it an acid?

Covalent:

Acid: Contains H+1 ion

Is the ionic Binary or

Polyatomic?

Binary Ionic Polyatomic Ionic

Rules for Binary Ionic Compounds

Name the metal ion from the chart– Watch for these five metals which have two common

charges: Cu, Fe, Sn, Pb, Hg– These must be named to specify which charge– Use either Roman numerals in parenthesis to show charge

or – Old Latin names with –ous ending for lower charge or –ic

ending for higher charge– Latin names: Cu= cuprum, Fe= ferrum, Sn= stannum Pb =

plumbum, Hg = mercur Name the non-metal from chart but change the

ending to -ide

Examples of Binary Ionic Compounds

NaCl Na is sodium Cl is chlorine so we name it sodium chloride

AlBr3 Al is aluminum Br is bromine so we call it aluminum bromide (the 3 is not named)

Cr2O3 Cr is chromium and O is oxygen so we name it chromium oxide

An example of the 5 special metals

PbI2 Pb is lead. Lead can have two charges (+2 and +4). We must specify which lead it is.

– To determine the form we look at the other ion, iodide– Iodide has a -1 charge. There are 2 iodides. So, the total is

2 x (-1) = -2– The lead must balance this charge so it is the +2 form– +2 is the charge of lead which is the lower charge– Use either a Roman numeral two (II) or the –ous ending

So, it is either lead (II) iodide or plumbous iodide

Rules for Polyatomic Ionics

Identify the group that acts as a single unit. This is called the polyatomic ion.

Name the positive “side” or metal portion– Watch for the same 5 metals as before– Only one polyatomic “metal” exists- NH4

+1

Name the non-metal or negative “side” using the oxidation/charge sheet– The names generally end with –ite or –ate

Examples of Polyatomics

NaHCO3 We identify HCO3-1 as the

polyatomic group. Na is sodium; the polyatomic group is bicarbonate. The name is sodium bicarbonate.

Ca(OH)2 The group in parenthesis is the polyatomic ion. It is hydroxide. Ca is calcium; the polyatomic group is hydroxide. The name is calcium hydroxide.

A “5 metal” example

Fe2(SO3)3 SO3-2 is the polyatomic group. Fe is

iron but it has multiple possible charges. The type must be specified. To determine the form of iron we look at the charge of SO3 -2. Three SO3

-2 would have a 3x(-2) = -6 charge. The iron must balance this. There are two irons so 2 Fe = +6. Fe is +3

+3 is the high charge for iron: SO3-2

is sulfite The name is either iron (III) sulfite or ferric sulfite

Rules for Acids

Acids have H+1 as the metal portion Separate H+1 from the rest of the molecule Determine the name of the non-metal If…

– The ion ends with –ide name acid as hydro___ic acid– The ion ends with –ite name acid as ___ous aicd– The ion ends with –ate name acid as ___ic acid

Acid means “H+1” ion as metal.

Acid Examples

HCl Cl is the non-metal. It would be named chloride. An –ide ending means name the acid as hydrochloric acid.

HNO2 NO2-1 is the non-metal. It is named

nitrite. An –ite ending means we name the acid as nitrous acid.

H3PO4 PO4-3 is the non-metal. It would be

named phosphate. An –ate ending means we name the acid as phosphoric acid.