Naming Compounds and Writing Formulas

Key Question:

Why Do Atoms Combine In Certain Ratios?

Review of Oxidation Numbers

Chemical Compound Quiz

Sodium chloride is a flavorful addition to many foods. What is the common name?

Salt

Review of Oxidation Numbers

All compounds have an electrical charge of zero (they are neutral).

An oxidation number indicates the charge on the atom (or ion) when electrons are lost, gained, or shared in chemical bonds.

Oxidation Numbers

A sodium atom always ionizes to become Na+ (a charge of +1) when it combines with other atoms to make a compound.

Therefore, we say that sodium has an oxidation number of 1+.

What is chlorine’s oxidation number?

H HeLi Be B C N O F NeNa Mg Al Si P S Cl Ar 1 2 3 4 5 6 7 8

H HeLi Be B C N O F NeNa Mg Al Si P S Cl Ar 1 2 3 4 5 6 7 8

The Number Of Electrons In The Outside Energy Level.

The Number Of Electrons In The Outside Energy Level.

You Might Be a Redneck If…

You take your dog for a walk and both use the same tree.You burn your yard rather than mow

it.

Ionic Bonds

On the periodic table, strong electron donors are on the left side (alkali metals).

Strong electron acceptors are on the right side (halogens).

The further apart two elements are on the periodic table, the more likely they are to form an ionic compound.

Covalent Bonds

Covalent compounds form when elements have roughly equal tendencies to accept electrons.

Elements that are both nonmetals and therefore close together on the periodic table tend to form covalent compounds.

Oxidation Numbers, Lewis Structures And Chemical Formulas

Remember, the oxidation numbers for all the atoms in a compound must add up to zero.

Multiple Oxidation Numbers

Some periodic tables list multiple oxidation numbers for most elements.

This is because more complex bonding is possible.

Naming Compounds and Writing Formulas

Naming Binary Ionic Compounds:At the conclusion of our time together, you should be able to:

1. Name a binary ionic compound with a metal that has one oxidation number using

standard naming procedures2. Name a binary ionic compound with a metal

that has multiple oxidation numbers using the Roman system

3. Write the formula of a binary ionic compound if given the name

6 Types Of Chemical Compounds

•Binary ionic - metal ion – nonmetal ion

•Binary molecular - two nonmetals

•Ternary ionic - at least one ion is a polyatomic ion

•Binary acid - H – nonmetal

•Ternary acid - H – Polyatomic ion

•Base - metal ion – OH

Naming Compounds with Ionic Bonds

Tips To Keep In Mind When Naming And Writing Formulas:

•Always keep your Periodic Table handy – You should have it in front of you ALWAYS when you are naming and writing formulas.

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

•NonmetalsNonmetals are found on the right side of the stairstep of the Periodic Table.

•Metalloids Metalloids are the 6 elements on or below the stairstep except Al, Po and At. For naming purposes they will tend to behave like nonmetals.

Naming Binary Compounds

A binary ionic compound is held together by ionic bonds.

Binary molecular compounds consist of covalently bonded atoms.

Each type of compound has its own naming rules.

How Do You Name Binary Ionic Compounds?

(Composed Of Two Elements – A Metal And A Nonmetal)

•Name the first ion

•From groups 1, 2, 3, 13, zinc, cadmium, or silver. (You must use a Roman Numeral with the name for the other metals – we’ll discuss this later.)

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

Naming Binary Ionic Compounds

MgBr2 is magnesium (name of first element) + brom (root name of second element) + ide suffix = magnesium bromide

ExamplesNaCl

Name the metal ionSodium

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

Chloride

CaO

Calcium Oxide

Al2S3

AluminumSulfide

MgI2

Magnesium Iodide

Redneck Hotel!

Examples

BaNa2You should recognize a problem with this one

This is two metals – not a binary ionic compoundThe name of this is BananaBanana (haha!!)

What is the name of this compound:

HIJKLMNO?

WATER – “H” to “O”

You have to admit – that was funny!

Exit Quiz

LiCl

Name the metal ionLithium

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

Chloride

CaSe

Calcium Selenide

Ga2S3

Gallium Sulfide

MgF2Magnesium Fluoride

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!!!

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 the compound to be neutral

Copper (I)Sulfide

MnO2Name the first ion. Since it is a transition metal, you must use a Roman Numeral.

How do you determine the Roman Numeral?

It is the same as the charge.

What is the charge of Mn?

•Oxygen (group 16) has a -2 charge and a total of -4 charge.

•There are two oxygens with one manganese.

•Therefore Mn must have a +4 charge for this compound to be neutral.

Manganese (IV)oxide

Things You Can LearnFrom Your Dog!!

• When it is hot outside, drink lots of water.

• Take naps.

Cu2O and CuO ____

Copper (II) oxide

Copper is +2

_____

Copper (I ) oxide

Copper is +1

So Why Must We Use Roman Numerals With Transition Elements?

•The metals in groups 1, 2, 3, and 13 have single, definite charges.single, definite charges.

•Group 1 metals have a +1+1 charge.

•Group 2 metals have a +2+2 charge.

•Groups 3 and 13 metals have a +3+3 charge.

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

For example, there are two copper oxide compounds:

We can’t just say Copper oxide. Which one of these is Copper oxide? We must distinguish these

by using a Roman Numeral

And Remember, There Are Three Transition Elements Which Do Not Require A Roman Numeral Because They

Have Single Definite Charges. These Are:

Zinc – Zn2+ Cadmium – Cd2+ Silver – Ag+

You need to remember the charges for these.

Ag2O Name the first ion.

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

oxide

ZnCl2Name the first ion.

Name the second ion changing the suffix to –ide.

Zinc chloride

No Roman Numerals needed for these.

How Do You Write Formulas For Binary Ionic Compounds Given The Name?

Two Simple Steps:

1. Write the symbol and charge of each ion

2. Balance the charges by providing subscripts

Magnesium chloride Write the symbol and charge of each ion

Mg2+ Cl-Balance the charges by supplying subscripts. Subscripts tell how many of each atom is present.You need a second Cl-1 to balance the charges

Cl-

MgCl2

Iron (III) bromide

Write the symbol and charge of each ion. The charge of the iron is provided by the Roman Numeral.

Fe3+ Br -

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 -

Br -

FeBr3

Aluminum Sulfide Write the symbol and charge of each ion.

Al3+ S2- 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?

2

3

Al3+ S2-

S2-

Al2S3

Jobs you get with a Chemistry Major

Writing Formulas a Little Quicker

Iron and oxygen combine to form a compound. Iron (Fe) has an oxidation number of 3+. Oxygen (O) has an oxidation number of 2–.

Predict the chemical formula of this compound.

Fe

3+ O

2-

32

Writing Formulas a Little Quicker

Simply cross the oxidation numbers and make them positive

Mn

4+ P

3-

43

Let’s Try Another One:

Manganese (IV) phosphide

Mn

4+ O

2-

42

Let’s Try One More:

Manganese (IV) oxide

MnO2

Cross but in this case they

must be dropped!

Naming Binary Ionic Compounds:Let’s see if you can:

1. Name a binary ionic compound with a metal that has one oxidation number using

standard naming procedures2. Name a binary ionic compound with a metal

that has multiple oxidation numbers using the Roman system

3. Write the formula of a binary ionic compound if given the name

Exit Quiz – Formula for magnesium chloride?Exit Quiz – Formula for magnesium chloride?

MgCl2

2+ 1-

Exit Quiz – Formula for sodium oxide?Exit Quiz – Formula for sodium oxide?

Na2O

1+ 2-

Exit Quiz – Name for:

Fe2O3

3+ 2-Iron (III) oxide

6-6+

Exit Quiz: Formula for Chromium (IV) oxide

CrO2

4+ 2-

2 4Cr O

Murphy's Lawsof

Science and Technology

Logic is a systematic method of coming to the wrong conclusion with confidence.

Naming Compounds and Writing Formulas II

6 Types Of Chemical Compounds

•Binary ionic - metal ion – nonmetal ion

•Binary molecular - two nonmetals

•Ternary ionic - at least one ion is a polyatomic ion

•Binary acid - H – nonmetal

•Ternary acid - H – Polyatomic ion

•Base - metal ion – OH

Naming Binary Molecular and Ternary Ionic Compounds:At the conclusion of our time together, you should be able to:

1. Name a binary molecular compound2. Name a ternary ionic compound with a metal

that has one and multiple oxidation numbers using the appropriate system

3. Write the formula of a binary molecular and ternary ionic compound if given the name

The Second Category of Compounds –

Binary Molecular

What are Binary Molecular Compounds?

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.

Naming – You Must Use Prefixes.

1 = mono 3 = tri 5 = penta 7 = hepta 9 = nona

2 = di 4 = tetra 6 = hexa 8 = octa 10 = deca

Steps

1. The first nonmetal only gets a numeric prefix when there is more than one. No prefix if there is only one.

2. The second element always gets a numeric prefix and always has a suffix of -ide

Naming Binary Molecular Compounds

As with binary ionic compounds, the ending of the name of the second element in the compound is modified by adding the suffix –ide.

Familiar Saying

Socially orientated individuals tend to congregate in gregariously homogenous groupings.

Birds of a feather flock together!!

CO2

Carbon dioxide

CO

Carbon monoxide

N2O4

Dinitrogen tetroxide

H2O

Dihydrogen monoxide

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.

AlCl3

What 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 name it aluminum chloride.

Given The Names Of Binary Molecular Compounds, How Do You Write The

Formulas?

Very easily done!!! The prefixes tell you how to write the formulas. DO NOT CONSIDER CHARGES. NONMETALS ARE ALL NEGATIVE SO TO USE

CHARGES DOES NOT WORK!

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

NO

Nitrogen 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!??

A Flow Chart For Naming Binary CompoundsA Flow Chart For Naming Binary Compounds

Redneck Innovations

Mr. T

My Students

Third Category Of Compounds – Ternary Ionic Compounds.

These Compounds Contain At Least One Polyatomic Ion.

What is a polyatomic ion?

Let’s look at the name to try to understand.

•It is an ionion – that means it has a charge.

•It is polyatomicpolyatomic – that means it is made of more than one atom.

Let’s look at some examples of polyatomic ions.

CO32- carbonate

This ion is composed of one carbon and three oxygens and the entire group

has a charge of -2.

Polyatomic ion – Group of atoms that act as a unit and carry a charge.

You have been given a list of other polyatomic ions

You need to learn these!!!

How Do You Recognize Ternary Ionic Compounds?

Composed of two ions in which at least one is a polyatomic ion.

There is only one positive polyatomic ion (NH4+1)

Three possible types of Ternary Ionic Compounds:

•Ammonium + negative ion (nonmetal)

•Metal (positive ion) + negative polyatomic ion

•Ammonium + negative polyatomic ion

Polyatomic Ion

Naming Compounds with Polyatomic Ions as Cations

NH4Cl is ammonium (the name of the ion from chart) + chlor (root name of the second element) + ide suffix = ammonium chloride.

Naming Compounds with Polyatomic Ions as Anions

1. Name the first ion.

2. Name the second ion. Isn’t that simple??!!

Examples:Na2CO3

When you look at this compound you should recognize that this is NOT binary. There are THREE elements present. When you see this, immediately look for a polyatomic ion. CarbonateCarbonate is present here.

Name the first ion.

Sodium

Name the second ion.

carbonate

Notice that you do NOT change the suffix – just name the polyatomic

ion

Fe(OH)3 Name the first ion.

Iron Remember that iron requires a Roman Numeral since it is a transition element. What Roman Numeral should be used?

The Roman Numeral comes from the charge of the ion. How do you find the charge of the iron?

You know two things:

•All compounds are neutral.

•You know the charge of OH (-1)

Since there are 3 OH groups, each with a -1 charge, the charge of the iron must be +3 for the compound to be neutral

(III)

Name the polyatomic ion.

hydroxide

NH4Cl Name the first ion.

Ammonium Name the second ion.chloride

Notice that since the second ion is a nonmetal that, like binary ionic compounds, the suffix of the nonmetal changes to –ide.

Looks like a monster, but it’s really a pussycat.

(NH4)3PO4

Name the first ion.

Name the second ion.Ammoniumphosphate

Naming Compounds with Polyatomic Ions as Cations and Anions

Cu2SO4Name the first ion.

CopperYou should realize that you need a Roman Numeral since copper is a transition metal.The Roman Numeral is the same as the charge.

What is the charge?

The charge of sulfate is -2.

Since there are two coppers, the charge of the copper must be +1.

(I) sulfate

Name the second ion.

Euphemisms in Science We all know that some politicians and government spokesmen use certain euphemistic phrases to give an aura of respectability

to descriptions of events or actions which would be offensive when expressed in plain English. The following is a list of

Euphemisms in Science and their translations into plain English.

“It has long been known...”

I haven't bothered to look up any references!

How Do You Write Formulas For Ternary Ionic Compounds?

Very Much Like Writing Formulas For Binary Ionic Compounds.

Three Steps:

1. Write the formulas/symbols of each ion.

2. Balance the charges by supplying subscripts.

3. If a subscript is needed for a polyatomic ion, it must be put in parentheses with the subscript on the outside.

Let’s do some!!

Aluminum nitrate First, you can tell from the name that there is a polyatomic ion present (nitrate). All binary ionic compounds have suffixes of –ide.

Write the formula/symbol and charge of each ion.

Al3+ NO3-

Balance the charges by supplying subscripts.

Since Al is +3 and NO3 is -1, you need a total of 3NO3-

to balance one Al3+

Since you will need a subscript of 3 for NO3-, you need

to put this in parentheses with the 3 outside.

Al(NO3)3

Lead (IV) acetate Write the formula/symbol and charge of each ion.

Pb4+ C2H3O2-

Balance the charges by supplying subscripts. Since Pb is +4 and C2H3O2 is -1, you will need 4 C2H3O2

-1 to balance 1Pb+4

Pb(C2H3O2)4

Calcium phosphateWrite the formula/symbol and charge of each ion.

Balance the charges by supplying subscripts. Since Ca is +2 and PO4 is -3, you will need 3 Ca+2 to balance 2 PO4

-3

Ca2+ PO43-

Ca3(PO4)2

Strategy For Naming Ternary Ionic Compounds.

What Do You Call A Detective Crossed With A Inner Transition

Metal?

Sherlock Holmium

Naming Binary Molecular and Ternary Ionic Compounds:Let’s see if you can:

1. Name a binary molecular compound2. Name a ternary ionic compound with a metal

that has one and multiple oxidation numbers using the appropriate system

3. Write the formula of a binary molecular and ternary ionic compound if given the name

CO2

Carbon dioxide

SO

Sulfur monoxide

N2O5

Dinitrogen pentoxide

CF4

Carbon tetrafluoride

SO3

Sulfur trioxide

CO

Carbon monoxide

B2O3

Diboron trioxide

NF5

Nitrogen pentafluoride

Exit Quiz

Exit Quiz

Al3+ combines with sulfate (SO4)2– to make aluminum sulfate.

Write the chemical formula for aluminum sulfate.

Al3+(SO4)

2-

32

Exit Quiz Answer

Mn

4+(PO4)

3-

43

Let’s Try Another One:

Manganese (IV) phosphate

Mn

4+(CO3)

2-

42

Let’s Try One More:

Manganese (IV) carbonate

Mn(CO3)2

Familiar Saying

It is fruitless to attempt to indoctrinate a superannuated canine with innovative maneuvers.

You can’t teach an old dog new tricks!