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Binomial Nomenclature

2 types of chemical compounds that we will

name:

•Binary ionic - metal ion – nonmetal ion

•Binary molecular - two nonmetals

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Tips to keep in mind when naming and writing formulas:

• Always keep your Periodic Table handy!

• Metals (except Hydrogen) are found to the left of the stairstep on the Periodic Table.

• Nonmetals are found on the right side of the Periodic Table.

• Transition Metals are found to the right of Group 2 to the stairstep (except aluminum which is a regular metal)

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Naming Binary Ionic Compounds5

When naming, metals always come before the non-metal (Al and F)• If the first ion is a transition element other than

zinc, cadmium, or silver, you must use a Roman Numeral with the name – we’ll discuss this later.

Name the first element as is and follow with the second element ending in “ide”

Examples

NaClName the metal

ionSodium

Name the nonmetal ion, changing the suffix to –ide.

Chloride

CaOCalcium Oxide

Al2S3

Aluminum Sulfide

MgI2

Magnesium Iodide

BaNa2

You should recognize a problem with this one

This is two metals – not a binary ionic compound. The name of this is Banana (JOKE – haha)

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What about the transition metals and using roman numerals? How does that work? Let’s see.

FeO Notice – metal and nonmetal.Name the first ion. Since the first ion is a transition

element, you must use a Roman Numeral to represent the charge.

How do you know the charge?Deductive reasoning.

All compounds are neutral.

Oxygen has a -2 charge (group 16)

Therefore ….. Iron must have a +2 charge since there is one iron and one oxygen. Iron gets a Roman

Numeral II.

Iron II Oxide

Isn’t this easy and FUN!!!

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Cu2SName the first ion. Since it is a transition metal, you must use a Roman Numeral.

Which Roman Numeral? The Roman Numeral is the same as the charge of the ion.

How do you find the charge?

Deductive reasoning!

All compounds are neutral

Sulfur has a -2 charge (group 16)

There are two coppers.

Therefore each copper must have a +1 charge for all ions to be neutral

Copper (I)Sulfide8

So why must we use Roman Numerals with transition elements?

The metals in groups 1, 2, and 3 have single, definite charges.

Group 1 metals have a +1 charge.

Group 2 metals have a +2 charge.

Group 13 metals have a +3 charge.

Transition metals may have multiple charges – usually two different positive charges.

For example, there are two copper oxide compounds:

Cu2O and CuO We can’t just say Copper oxide. Which one of these is Copper oxide? We must distinguish these by using a Roman Numeral

Cu2O

Copper (I) oxide

Copper is +1

CuO

Copper (II) oxide

Copper is +2

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There are three transition elements which do not require a Roman Numeral because they have single definite charges. These are:

Zinc – Zn+2

Cadmium – Cd+2

Silver – Ag+1

You need to remember the charges for these.

Ag2O Name the first ion.

Silver Name the second ion changing the suffix to –ide.

oxide

ZnCl2 Name the first ion.

Name the second ion changing the suffix to –ide.Zinc chloride

No Roman Numerals needed for these.

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Sometimes you will see the transition elements named using common names. Transition metals named with Roman Numerals involves stock names.

• The common names use the Latin derivative of the element’s name with a suffix of either –ous or –ic.

• The –ous suffix name corresponds with the smaller charge.

• The –ic suffix name corresponds with the larger charge.

Cuprous = Copper (I)

Cupric = Copper (II)

Ferrous = Iron (II)

Ferric = Iron (III)

Plumbous = Lead (II)

Plumbic = Lead (IV)

There are many more – just be familiar with these six common names.

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Stock name Common NameCopper I Cuprous

Copper II Cupric

Iron II Ferrous

Iron III Ferric

Lead (II) Plumbous

Lead (IV) plumbic

In Summary

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The Next Category of Compounds – Binary Molecular

These compounds contain two elements (binary).

The term “molecular” indicates that these elements are joined by a covalent bond.

They must therefore be nonmetals.

Bottom line – 2 elements – both nonmetals

To name and write formulas for these, you must know some numerical prefixes.

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Naming Covalent Bonds14

To name covalent compounds we use numerical prefixes to tell the # of atoms of each element in a molecules.

Exception- Don’t use mono- before the first element Wrong- CO- monocarbon monoxide Correct- CO- carbon monoixde

Just like ionic bonds, the ending of the second element is still changed to “ide”.

Prefix Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca

Number 1 2 3 4 5 6 7 8 9 10

CO2

Carbon dioxide

CO

Carbon monoxide

N2O4

Dinitrogen tetraoxide

CCl4

Carbon tetrachloride

Name the first element. Since there is only one, no prefix is needed. The second element

always gets a prefix and a suffix of –ide.

Name the first element. Since there are two

present, the prefix “di” is needed. The second

element always gets a prefix and a suffix of –ide.

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AlCl3What do you think about this one???

Be careful. This is a metal and nonmetal.

Always keep your Periodic Table in front of you for reference.

You may have been tempted to say “aluminum trichloride”. This is INCORRECT!

This is a binary IONIC compound. No prefixes are used. Simply aluminum chloride.

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Silicon dioxide

Diphosphorous pentachloride

Silicon and oxygen are both nonmetals.

The lack of a prefix on silicon means that there is only ONE silicon.

The prefix “di” in front of oxide means that there are TWO oxygens.

SiO2

Phosphorous and chloride are both nonmetals.

The prefix “di” means that there are TWO phosphorouses (Is that a word?)

The prefix “penta” before chlorine means that there are five chlorines.

P2Cl5

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You Try!

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S, O

S, F

C,Cl

N,I

SO2, sulfur dioxide

SF2,sulfur difluoride

CCl4, Carbon tetrachloride

NI3,Nitrogen triiodide

NONitrogen monoxide Nitrogen and oxygen are both

nonmetals.

The lack of a prefix on nitrogen means only ONE nitrogen.

The prefix “mono” on oxygen indicates ONE oxygen.

Is this not sooooooo easy!??

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Reivew!!!20

1. P4S5

2. N2O3

3. Na3N

4. Ni2S3

5. CuF2

6. CoS7. CsI8. Cl2O

Prefix

Hydro-

Stem or root of nonmetal

< NM >

Suffix

-ic Acid

HCl Hydro

HI Hydro

HCl is a binary acid – hydrogen - nonmetal

chloric Acid

iodic Acid

H2S Hydrosulfuric Acid

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Writing Formulas for Ionic Compounds22

1. List the symbol for each ion and its charge Ie. Al3+F-

2. Find the least common multiple of the ion’s charges to make the compound neutral

The least common multiple of 3 and 1 is 3 You only need 1 Al but 3 F

3. Write out the formula with subscripts AlF3

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Ionic Formulas- Criss-Cross MethodCross down the charge numbers and write

the correct formulas for the following cations and anions. Let’s try it with Mg and Br

 

You Try! Write out the formula and its name!24

Li, O

K, Cl

Br, Ba

Li2O, Lithium Oxide

KCl, Potassium Chloride

BaBr2, Barium Bromide

More examples: Iron (III) bromideWrite the symbol and charge of each ion. The charge of the iron is provided by the Roman Numeral.

Fe+3 Br -1

Balance the charges by supplying subscripts. The subscripts tell how many of each ion is needed to balance the compound.

You’ll need three bromine ions to balance the one iron.

Br -1

Br -1

FeBr3

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Aluminum Sulfide

Write the symbol and charge of each ion.

Al+3 S-2

Balance the charges by supplying subscripts.

In this case the charges do not evenly divide into each other. You must find the least common multiple. SIX

How many aluminums are needed to arrive at a +6 charge?

How many sulfurs are needed to arrive at a -6 charge?

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3

Al+3 S-2

S-2

Al2S3

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Formulas for Molecular Compounds27

Write the symbols for the first and second element

Translate the prefixes into subscripts. Ie.

Xenon Hexafluoride XF6

You aren't balancing charges of covalent compounds!

You Try! Write out the formula for each compound!28

Diarsenic pentoxide

Tetraphosphorus trisulfide

Tetraphosphorus decoxide

Phosphorus trichloride

As2O5

P4S3

P4O10

PCI3