Naming Polyatomic ions (P.A. Ions)

The Root Ions (on the board)

• Carbonate CO32-

• Nitrate NO3-

• Sulfate SO42-

• Chlorate ClO3-

• Phosphate PO43-

• Chromate CrO42-

• Acetate C2H3O2-

Common Exceptions

• Ammonium NH4+

• Hydronium H3O+

• Hydroxide OH-

• Peroxide O22-

• Cyanide CN-

Rules to Naming P.A. Ions

1. Change the suffix of the root ion from –ate to –ite when you subtract one Oxygen

Example: Sulfate = SO4

2-

Subtract 1 Oxygen = SO32- = sulfite

Rules to Naming P.A. Ions

2. Change the prefix to hypo- and the suffix to -ite when subtracting one Oxygen from the -ite form.

Example: Sulfite = SO3

2-

Subtract 1 oxygen = SO22- hyposulfite

Rules to Naming P.A. Ions

3. Change the prefix to per- and the ending to -ate when you add one Oxygen to the

root form.Sulfate = SO4

2-

Add one oxygen = SO52- = persulfate

More Root PA Ions

• Bromate BrO3-

• Iodate IO3-

• Manganate MnO3-

Additional Rules to Naming

• Change an Oxygen to a Sulfur, add the prefix thio- to the Root ion name– Example:Sulfate = SO4

2-

Thiosulfate = add 1 sulfur and subtract 1 oxygenThiosulfate = SO4

2- +1 S -1 O = S2O32-

Adding Counter Ions

• Adding Hydrogen ions (H+)– Add the word Hydrogen to the prefix• Follows the numbering prefix system

– Example:• Hydrogen Sulfate (Charges are conserved)

H+ + SO42- = HSO4

-

• Dihydrogen Sulfate (Charges are conserved)2H+ + SO4

2- = H2SO4

Adding Counter Ions

• Lets try another one together– Hydrogen Phosphate• H+ + PO4

3- = HPO4⃝ -

• 1 positive charge + 3 negative charges = 2 negative net charge• 1 + (-3) = 2-• H+ + PO4

3- = HPO42 -

Adding Counter Ions

• Lets try one more with Hydrogen• 2H+ + PO4

3- = H2PO4⃝ -

• 2 positive charges + 3 negative charges equals 1 negative net charge

• 2 + (-3) = -1• 2H+ + PO4

3- = H2PO41 -

What is the name of this compound?

Adding Counter Ions

• Counter Ions from group 1A, 2A & 3A follow the following rule:– Name of element + name of Polyatomic anion• Charges must be conserved Example:Sodium PhosphateNa+ + PO4

3-

Na3PO4

Note*- It takes 3 positive charges to conserve 3 negative charges

Adding Transition Metals

• Transition metals can have different oxidation states (levels of electron deficiency) stated as roman numerals– Example: Fe (I), Fe (II), Fe (III)• Fe (I) = Fe1+

• Fe (II) = Fe2+

• Fe (III) = Fe3+

Adding Transition Metals

• Charges must be conserved (ions must add up to zero net charge if not explicitly stated)– Example: Iron (II) Sulfate• Fe2+ + SO4

2- = Fe2(SO4)2

• Subscripts can be reduced• Answer = Fe(SO4)

Adding Transition metals

• Charge, again, must be conserved– Example: Gold (III) Nitrate– Au3+ + NO3

- = ?– It takes three Nitrates to counterbalance one Gold

ion– 3 positive charged + 3 x (-1) = 0– Answer = Au(NO3)3

Acids / Bases

• Three types of Acids– Lewis Acid– Brǿnstead Acid We will focus on this one– Arrhenius Acid

Brǿnstead Acid

• In a reaction, a molecule that gives a H+ ion.– Example: HCl + NaOH NaCl + HOH

• Common acids– Sulfuric Acid H2SO4

– Phosphoric Acid H3PO4

– Hydrochloric Acid HCl– Nitric Acid HNO3

How to name acids

• Acid general equation:HnX Where H = Hydrogenn = subscript numberX = anion (could be one atom or a P.A. anion)– The key to naming is determining what X is.

How to name acids

• If the anion ending is –ide then you must:1. Add hydro- to the prefix2. Change the suffix from –ide to –ic3. Add the word acid to the end of the word.Example:HCl The anion is Chloride Using the rules, it becomes hydrochloric acid

Another Example

• HF– Using normal naming, it would be Hydrogen

Fluoride– Now switch to make it an acidWhat is the answer?

Hydrofluoric acid

Naming Acids

• If the X anion ends in –ate then you must1. Change the –ate ending to –ic 2. Add the word acid to the endExample:H2SO4 = Dihydrogen Sulfate

Answer: Sulfuric acid

Naming Acids

• If the X anion ends in –ite then you must1. Change the –ite ending to –ous 2. Add the word acid to the endExample:H2SO3 = Dihydrogen Sulfite

Answer: Sulfurous acid

Bases

• Three types of bases– Lewis base– Brǿnstead base We will focus on this one– Arrhenius base

Brǿnstead base

• A base that accepts a H+ ionExample: HCl + NaOH NaCl + HOH

Base in blueCommon Bases:1. Hydroxide (OH-)2. Ammonia (NH3)

3. Water H2O

Naming a base

• Follows the same rules as naming other ionic compoundsExample: Al3+ + OH- Al(OH)3

Answer: Aluminum Hydroxide

Naming Molecular Compounds

• These compounds are not ionic, but rather they are covalent

• Example: – CH4

– SiF4

– H2O

– C2H6O

How to name molecular compounds

1. Determine if a compound is ionic or molecular (based on electronegativity)

2. Start with the first element– Give its alphanumeric number prefix– Give its name

3. Go to the second element– Give its alphanumeric number– Give its name

How to name molecular compounds

4. Repeat Step 3 until all atoms are taken into account.

5. On the last atom, add the ending –ide.

Prefixes

• Mono = 1• Di = 2• Tri = 3• Tetra = 4• Penta = 5• Hexa = 6• Hepta = 7• Octa = 8

• Nona = 9• Deca = 10• Undeca = 11• Dodeca = 12• Trideca = 13• Tetradeca =14(we will go up to 19)

Examples

• C8H18

• Answer = octacarbon • Answer – octacarbon octadecahydride

Count the first element

Compound has 8 carbon atoms

Put the prefix octa- in front of the atom carbon

Go to the next atom

Compound has 18 Hydrogen atoms

Add the prefix octadeca to the word hydrogen

Since Hydrogen is the last element in the compound, switch the ending to –ide.

More Examples

• SiS2

• Answer = monosilicon disulfide

• NO2

• Answer = mononitrogen dioxide

Law of Definite Proportions

• A compound must have the same ratio of atoms in it at all times. – Example: H2O – There must be 2 Hydrogen atoms for every 1

oxygen atom.

Mass & the law of definite proportions

• Similarly, the mass of each atom in the compound must also follow the same ratio. – Example: H2O– If we have 2 grams of hydrogen, we must always

have 16 grams of Oxygen– The ratio is always 1:8 for water

Example:

• You have to test one unknown liquid to see if it is water. You have a sample of water that you know (standard).

• Is the unknown compound water?

H O

Known 4.0 g 32.0 g

Unknown 2.0 g 32.0 g

Example (Cont)

• Set up the ratios:

• Does 1/8 = 1/16?

H O

Known 4.0 g 32.0 g

Unknown 2.0 g 32.0 g

Compound 1 (known)

Compound 2 (unknown)

H 4.0 g 2.0 g

O 32.0 g 32.0 g