11 NAMING AND FORMULA-WRITING

Chemical Nomenclature

Naming and Formula-writing

1. Binary Ionic Compounds – Univalent Cation 2. Binary Ionic Compounds – Multivalent Cation 3. Ionic Compounds & Polyatomic (Complex) Ions 4. Hydrated Ionic Compounds

5. Binary Covalent Compounds 6. Binary Acids

Definitions

 An IONIC COMPOUND consists of a metal

cation bonded to a nonmetal anion.

Electrostatic attraction holds them together.

 A COVALENT COMPOUND consists of two

nonmetal atoms sharing valence electrons.

 A BINARY compound is one that is made of

Univalent Binary Ionic Compounds

only ONE possible charge.

Na+ Zn2+ Al3+ Ca2+

sodium zinc aluminum calcium

The charges are memorized or predicted using a periodic table!

 The cations are bonded to nonmetal anions:

O2- N3- F- Br

oxide nitride fluoride bromide

Binary Ionic Compounds

metal bonded to non-metal

Naming:

MgCl

magnesium chlorine ide

Binary Ionic Compounds

Writing the chemical formula:

calcium oxide

Ca

O

2+ 2

-Total charge

must equal zero, so you need one of each:

1(+2)+1(-2)=0

 In an ionic compound, the charges of the

cations and anions must always cancel out.

 Subscripts are used if more than one atom is

needed to cancel the charges:

sodium chloride: Na+ and Cl-  NaCl

lithium oxide: Li+ and O2-  Li 2O

aluminum bromide: Al3+ and Br -  AlBr 3

zinc nitride: Zn2+ and N3-  Zn

3N2

magnesium carbide: Mg2+ and C4-  Mg 2C

Examples: Univalent Binary Ionic Compounds

Write the formulas:

• potassium oxide

• zinc chloride

• silver sulfide

• aluminum nitride

• gallium oxide

• calcium iodide

Write the names:

• K

3N

• AgI

• ZnBr

2

• Al

2O3

• Ba

3P2

Multivalent Binary Ionic Compounds

 These are ionic compounds where the metal

cation is multivalent, it can form different charges.

Fe2+ iron (II) Fe3+ iron (III)

Ni2+ nickel (II) Ni3+ nickel (III)

Co2+ cobalt (II) Co3+ cobalt (III)

Cu+ copper (I) Cu2+ copper (II)

Au+ gold (I) Au3+ gold (III)

Sn2+ tin (II) Sn4+ tin (IV)

An older system uses suffixes and Latin names, -ous for the lower charge, -ic for the higher charge:

Classical Naming of

Multivalent Ionic Compounds

If the metal cation is multivalent, there is an older system that uses suffixes and Latin names:

‘ic’ suffix means the higher charge, ‘ous’ suffix means the lower charge:

Fe2+ ferrous Fe3+ ferric

Pb2+ plumbous Pb4+ plumbic

Hg1+ mercurous Hg2+ mercuric

Cu+ cuprous Cu2+ cupric

Au+ aurous Au3+ auric

Sn2+ stannous Sn4+ stannic

Naming:

PbI

lead iodide

Ionic Compounds with

Multivalent Metals

Pb I

4 1

Charge on each Iodine is 1- charge on 4 Iodines is

4 x (-1) = -4

So the charge on Pb must be +4

(IV)

Naming:

Ionic Compounds with

Multivalent Metals

lead (IV) iodide

Change to “OUS/IC” system

lead (IV) iodide

2+ 4+

“ous” “ic”

Ionic Compounds with

Multivalent Metals

Writing the chemical formula:

cupric chloride

copper (II) chloride

Cu

Cl

2+ 1

Examples: Multivalent Binary Ionic

Compounds

Write the formulas:

• iron (II) oxide

• _{copper (II) chloride}

• tin (IV) sulfide

• cupric nitride

• _{nickel (III) oxide}

• ferrous iodide

• cobalt (III) selenide

Write the names:

• Fe₂O₃

• _SnS

• NiBr₂

•_CuS

• Pb₃P₂

• _CuBr

Polyatomic (Complex) Ions

 All of the cations and anions so far have been simple

ions - single atoms that have lost or gained electrons.

 A molecule is a particle that forms when two or more

atoms bond together.

 A complex ion is a charged molecule. Complex ions

may be cations or anions. examples:

-Naming:

Na

SO

sodium sulfate

= sodium sulfate

Ionic Compounds with

Polyatomic Ions

Writing the chemical formula:

calcium chlorate

Ca

ClO

2+ 1

Writing formulas with Complex Ions

a) ammonium chloride NH₄Cl

b) silver sulfate Ag₂SO₄

c) aluminum hydroxide Al(OH)₃

d) calcium phosphate Ca₃(PO₄)₂

e) iron (III) nitrite Fe(NO₂)₃

f) copper(II) permanganate Cu(MnO₄)₂

g) ammonium dichromate (NH₄)₂Cr₂O₇

Ionic Compounds with

Polyatomic Ions

Meanings of prefixes and suffixes of polyatomic ions:

Prefix and suffix Number of

oxygen atoms

Example

Hypo_____ite X-2 oxygen atoms ClO- hypochlorite

_____ite X-1 oxygen atoms ClO

2- chlorite

_____ate X oxygen atoms ClO

3- chlorate

Binary Covalent Compounds

 Covalent compounds are made of two NONMETAL

elements sharing valence electrons.

 There are no ions involved!!

 Because there are no charges to help us write the

formulas of covalent compounds, prefixes are used to indicate the number of each atom present in the

formula.

CO₂ is named “carbon dioxide”

CO is named “carbon monoxide” N₂O is named “dinitrogen monoxide” SO₃ is named “sulfur trioxide”

The prefix, “mono” is never used for

Naming Molecular Compounds

non-metal bonded to non-metal

Use prefixes to show the number of each

type of atom

1- mono

2 - di

3 - tri

4 - tetra

5 - penta

6 - hexa 7 - hepta 8 - octa

9 - nona

10 - deca

• Do not put ‘mono’ in front of the first element

Examples of Molecular Naming

PH3 phosphorus trihydride

PI3 phosphorus triiodide

CO carbon monoxide CO2 carbon dioxide

CCl4 carbon tetrachloride

NO nitrogen monoxide NO2 nitrogen dioxide

N2O dinitrogen monoxide

NO3 nitrogen trioxide

Examples of Covalent Naming

 Write the names:

SO₂ sulfur dioxide

P4O10 tetraphosphorus decoxide

 Write the formulas:

Naming:

H

SO

sulfuric acid OXYACID

ACIDS

Most acids have hydrogen

but not all hydrogens are acidic (come off)

Naming:

HCl

Binary Acids

 A simple definition of an “acid” is a substance which

produces H+ ions in water.

 Most acids have hydrogen ions in their formulas.

 A binary acid composed of a hydrogen cation bonded

to one other element:

HCl HBr H₂S

hydrochloric acid hydrobromic acid hydrosulfuric acid

Binary Acids

formula classical/acid name

HF hydrofluoric acid

HCl hydrochloric acid

HBr hydrobromic acid

HI hydroiodic acid

H2S hydrosulfuric acid

NOT hydrosulfic acid

H2Se hydroselenic acid

IUPAC/Stock name hydrogen fluoride hydrogen chloride

Oxy-Acids

 An acid can also be made of a hydrogen ion bonded to a complex

ion.

Complex ions whose names end in “ate”:

NO₃- _SO

42- CO32- PO4

3-nitric acid: HNO₃ sulfuric acid: H₂SO₄ carbonic acid: H₂CO₃

phosphoric acid: H₃PO₄

Can you propose a rule for naming oxy-acids

More Oxy-Acids

 Complex ions ending in “ite”:

NO₂- SO

32- ClO- ClO2

-nitrous acid: HNO₂

sulfurous acid:H₂SO₃

hypochlorous acid: HClO

chlorous acid HClO₂

Can you propose a rule for naming oxy-acids

ACIDS!!!

Meanings of prefixes and suffixes of polyatomic ions: Prefix and suffix

+ acid

Number of oxygen

atoms

Example

Hypo_____ous X-2 oxygen

atoms PO2

3- _{hypophosphorous acid}

_____ous X-1 oxygen

atoms PO3

3- phosphorous acid

_____ic X oxygen

atoms PO4

3- phosphoric acid

Per_____ic X+1 oxygen

atoms PO5

ACIDS

Writing the chemical formula:

Hypobromous acid

BrO

H

1+ ₁

Hydrated Ionic Compounds

 A HYDRATE is a salt that has water molecules

trapped within its crystals.

 Every hydrate has a certain number of water

molecules associated with each formula unit of the ionic compound. The number of water molecules is indicated by using prefixes.

mono hexa

di hepta tri octa tetra nona penta deca

CuSO₄ · 5 H₂O

copper (II) sulfate pentahydrate MgCO3 ·10 H2O

HYDRATED SALTS

Writing the name:

Name of compound (using proper rules) (prefix)hydrate

Tin (II) chlorate

pentahydrate

HYDRATED SALTS

Writing the chemical formula:

Formula of compound (using proper rules) #H2O

Copper (II) hypoiodite tetrahydrate

Examples of hydrates:

 Write the formulas:

copper(II) fluoride tetrahydrate CuF₂ ·4 H₂O

calcium nitrate trihydrate Ca(NO₃)₂ ·3 H₂O

 Write the names:

MgSO₄ · 7 H₂O magnesium sulfate heptahydrate

 If an ion carries a charge like “-2” or “-3”, a series of

related ions can be formed by adding hydrogen cations (H+) while still leaving a net charge:

examples:

Sulfide: S2- hydrogen sulfide: HS

-(bisulfide)

Sulfate: SO₄2- _{hydrogen sulfate: HSO}

4

-(bisulfate)

Carbonate: CO₃2- _{hydrogen carbonate: HCO}

3

-(bicarbonate)

-ACID SALTS

Writing the name:

sodium

Na

HPO

1) Name the cation

2) hydrogen is written second with the appropriate prefix if needed (so if it is “mono”, then you don’t need to write it)

3) Name of anion is written last

ACID SALTS

Writing the chemical formula:

aluminum dihydrogen phosphate

( PO

)

1) Write the formula for the anion and its charge

3-

2) Write the appropriate number of hydrogen atoms

H

3) For every H you add, add 1+ to the charge of the polyatomic ion

1-

4) Write the cation and its charge

Al

5) multiply ions until charges add to 0

More Formulas with Complex Ions

a) Sodium bicarbonate NaHCO₃

b) Nickel (II) hydrogen sulfide Ni(HS)₂

c) Aluminum perchlorate Al(ClO₄)₃

d) Barium dihydrogen phosphate Ba(H₂PO₄)₂

e) Iron (III) sulfite Fe₂(SO₂)₃

f) Cuprous bisulfateCuHSO₄

g) Zinc periodate Zn(IO₄)₂

DOUBLE SALTS

Writing the name:

Sodium

NaFePO

1) Name the first cation

2) Name of second cation with appropriate prefix (except “mono”)

3) Name of anion is written last

DOUBLE SALTS

Writing the name:

Sodium

NaFePO

iron (II)

phosphate

Why is this a 2?

NaFe PO

1+ X = 3 X = 3-1 X = 2

DOUBLE SALTS

Writing the name:

Sodium

NaFe

(CN)

1) Name the first cation

2) Name of second cation with appropriate prefix (except “mono”)

3) Name of anion is written last

DOUBLE SALTS

Writing the name:

Sodium

NaFe

(CN)

diiron

cyanide

What number goes here?

NaFe CN

1+ 2X = 5 2X = 5-1

X = 2

-1 x 5 cyanide molecules = -5

Must total 5+

DOUBLE SALTS

Writing the formula:

K

Potassium disilver phosphate

1) Write the chemical formula for first cation + its charge

2) Write the chemical formula for the second cation + its charge

3) Write the chemical formula for the anion + its charge

Ag

PO

3-DOUBLE SALTS

• NaTl(NO₃)₂

• MgNH₄PO₄ • 6H₂O

• AlK(SO₄)₂ • 9H₂O

• sodium thallium (I) nitrate • magnesium ammonium

phosphate hexahydrate

• aluminum potassium sulfate nonahydrate

• KMgF₃

• KNaCO₃

• NaNH₄HPO₄ • 4H₂O

• potassium magnesium fluoride • potassium sodium carbonate • ammonium sodium hydrogen