Ionic Nomenclature

Bellwork:

Is there an abrupt or gradual change between ionic and covalent bonds? Explain.

There is a gradual change. We get this change by noting the relative positions of the bonding elements across the periodic table. If they are close together toward the upper right hand corner, then the bond is more covalent. When the elements are on opposite sides of the periodic table, the chemical bond between them is more ionic. For the bonding of atoms between these two extremes, the bonding tends to be a blend of both, which is also referred to as polar covalent. This change can also be noted by electronegativity differences. Since values determine the type of bond, and the values can have varying amounts, the change is as gradual as those differing amounts are.

(p. 203 – 211)

Ch. 7 - Ionic Nomenclature

3.1.2 Determine the formula of an ionic compound formed between two given ions.

3.1.3 Name an ionic compound given its formula.

OBJECTIVES OBJECTIVES

The total number of natural and synthetic chemical The total number of natural and synthetic chemical compounds runs in the compounds runs in the millionsmillions. For some of these . For some of these

substances, certain common names remain in everyday substances, certain common names remain in everyday use. For example, calcium carbonate is better known as use. For example, calcium carbonate is better known as limestone, and sodium chloride is usually referred to as limestone, and sodium chloride is usually referred to as

table salt. table salt.

Unfortunately, common names usually give Unfortunately, common names usually give no informationno information about chemical composition. To describe the atomic about chemical composition. To describe the atomic

makeup of compounds, chemists use makeup of compounds, chemists use systematic methods systematic methods for naming compoundsfor naming compounds and for and for writing chemical formulaswriting chemical formulas. . You will learn the rules used to identify simple chemical You will learn the rules used to identify simple chemical

compounds.compounds.

You need to memorize the list of You need to memorize the list of polyatomic ions on the following page polyatomic ions on the following page

for your quiz and test.for your quiz and test.

More extensive lists can be found on More extensive lists can be found on pages 205 & 210 of your book.pages 205 & 210 of your book.

They may help you in memorization, They may help you in memorization, because they are broken down by because they are broken down by

charges.charges.

cadmium Cd 2+ chromium(II) Cr 2+ chromium(III) Cr 3+ cobalt Co 2+ copper(I) Cu + copper(II) Cu 2+ iron(II) Fe 2+ iron(III) Fe 3+

nitrate NO3−

nitrite NO2−

oxalate C2O42−

hypochlorite ClO −

chlorite ClO2−

chlorate ClO3−

perchlorate ClO4−

permanganate MnO4−

phosphate PO43−

dihydrogen phosphate H2PO4−

hydrogen phosphate HPO42−

hydrogen sulfate HSO4-

sulfate SO42−

sulfite SO32−

cyanide CN-

lead(II) Pb 2+ lead(IV) Pb 4+

manganese(II) Mn 2+

mercury(I) Hg22+

mercury(II) Hg 2+ nickel Ni 2+ silver Ag + tin(II) Sn 2+ tin(IV) Sn 4+ zinc Zn 2+

ammonium NH4+

acetate C2H3O2−

bicarbonate HCO3−

carbonate CO32−

chromate CrO42−

dichromate Cr2O72−

hydride H −

hydroxide OH −

Common Monatomic

Ions

Common Polyatomic

Ions

Common Ion Charges1+2+ 3+ NA 3- 2- 1-

0

Ionic Nomenclature

Oxidation numbers-- (oxidation states)—General distribution of electrons among the bonded atoms in a molecular compound or a polyatomic ion.

Ions formed from a single atomIons formed from a single atom

Group 1Group 1 metals lose 1 electron to give metals lose 1 electron to give 1+1+ cations (Na cations (Na++))Group 2Group 2 metals lose 2 electrons to give metals lose 2 electrons to give 2+2+ cations (Mg cations (Mg2+2+))

Group 17Group 17 elements gain 1 electron to give elements gain 1 electron to give 1-1- anions (Cl anions (Cl--))Group 16Group 16 elements gain 2 electrons to give elements gain 2 electrons to give 2-2- anions (O anions (O2-2-))Group 15Group 15 elements gain 3 electrons to give elements gain 3 electrons to give 3-3- anions (N anions (N3-3-))

Elements from the Elements from the d-blockd-block elements form elements form 2+, 3+2+, 3+ (or, in a few (or, in a few cases, 1+ cations)cases, 1+ cations)

–Cu forms 1+ and 2+ cationsCu forms 1+ and 2+ cations–Fe and Cr form 2+ and 3+ cationsFe and Cr form 2+ and 3+ cations–Be familiar with the others as wellBe familiar with the others as well

Assigning Oxidation Numbers The following is a list of guidelines for assigning The following is a list of guidelines for assigning

oxidation numbers (see book for more details):oxidation numbers (see book for more details): The atoms in a pure element have an oxidation number of zero.The atoms in a pure element have an oxidation number of zero. The more eThe more e--neg element in a binary compound is assigned the neg element in a binary compound is assigned the

number equal to the negative charge it would have as an anion. number equal to the negative charge it would have as an anion. The less eThe less e--neg atom is assigned the number equal to the positive neg atom is assigned the number equal to the positive charge it would have as a cation.charge it would have as a cation.

Fluorine has an oxidation number of -1 in all compounds.Fluorine has an oxidation number of -1 in all compounds. Oxygen has an oxidation number of -2 in almost all compounds.Oxygen has an oxidation number of -2 in almost all compounds. Hydrogen has an oxidation number of +1 in all compounds Hydrogen has an oxidation number of +1 in all compounds

containing elements that are more econtaining elements that are more e--neg than it; it has an oxidation neg than it; it has an oxidation number of -1 in compounds with metals.number of -1 in compounds with metals.

The algebraic sum of the oxidation numbers of all atoms in a The algebraic sum of the oxidation numbers of all atoms in a neutral compound is equal to zero.neutral compound is equal to zero.

The algebraic sum of the oxidation numbers of all atoms in a The algebraic sum of the oxidation numbers of all atoms in a polyatomic ion is equal to the charge of the ion.polyatomic ion is equal to the charge of the ion.

Although rules 1-7 apply to covalently bonded atoms, oxidation Although rules 1-7 apply to covalently bonded atoms, oxidation numbers can also be assigned to atoms in ionic compounds.numbers can also be assigned to atoms in ionic compounds.

Naming Monatomic IonsMonatomic Monatomic cationscations are identified simply by the are identified simply by the element’s name.element’s name.Examples: Examples:

– – KK

– Mg Mg

++

• Potassium cationPotassium cation2+2+

• Magnesium cationMagnesium cation

– Ca Ca 2+2+

• Calcium cationCalcium cation

– Al Al 3+3+

• Aluminum cationAluminum cation

Naming Monatomic IonsFor monatomic For monatomic anionsanions the the ending of the element’s name is dropped and the ending ending of the element’s name is dropped and the ending –ide–ide

is addedis added to the root name. to the root name.Examples: Examples:

– – FF

– ClCl

--

• FluorFluorideide anion anion

--• ChlorChlorideide anion anion

– SS 2-2-

• SulfSulfideide anion anion

– NN 3-3-

• NitrNitrideide anion anion

I. Binary Ionic CompoundsCompounds composed of Compounds composed of twotwo different elements different elements

Basic idea: Sum of the charges must add to zero.

•That is the sum of the cation charge and the sum That is the sum of the cation charge and the sum of the anion charge must cancel each other so that of the anion charge must cancel each other so that the compound form is neutral.the compound form is neutral.

cation (charges)anion (charges)

XXMMnn X Xmm

Criss-Cross Method1.1. Write the symbols for the ions side by side. Write Write the symbols for the ions side by side. Write

the cation first.the cation first.• AlAl3+3+ OO2-2-

2.2. Cross over the charges by using the absolute value Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other of each ion’s charge as the subscript for the other ion.ion.• AlAl22 OO33

3. Check the subscripts and divide them by their 3. Check the subscripts and divide them by their largest common factor to give the smallest possible largest common factor to give the smallest possible whole-number ratio of ions. Then write the whole-number ratio of ions. Then write the formula.formula.• AlAl22OO33

• For Al: 2 x 3For Al: 2 x 3++ = 6 = 6++ For O: 3 x 2For O: 3 x 2-- = 6 = 6--

Example 1: Calcium and Oxygen

Calcium Ca2+ Ca2+

Oxide O2-

O2-

Ca2O2

Criss-Cross Method

CaO

Example 2: Magnesium and Phosphorus

Magnesium

Mg2

+Mg2

+

Phosphorus

P3-

P3-

Mg3P2

Criss-Cross Method

Naming Binary CompoundsNomenclatureNomenclature- naming system- naming system

Involves combining the names of the compound’s positive and negative ions

The name of the cation is given first, followed by the name of the anion.

Al2O3Name of cation

aluminum

Name of anionoxide

Sample Problem 7-1

Write the formulas for the binary ionic compounds Write the formulas for the binary ionic compounds formed between the following elements:formed between the following elements:

A. lithium and fluorineB. lithium and oxygen

II. Stock system (roman numerals)

Example:Example:

Fe2+• Iron(II)Iron(II)

Fe3+• Iron(III)Iron(III)

CuCl• copper(I) chloridecopper(I) chloride

CuCl2• copper(II) chloridecopper(II) chloride

Sample Problem 7-2

a. Write the formula and give the name for the a. Write the formula and give the name for the compound formed from the ions Crcompound formed from the ions Cr3+3+ and F and F--..

b. Write the name for Cub. Write the name for Cu33NN22..

III. Polyatomic Ions

A A chargedcharged group of group of covalentlycovalently bonded bonded atomsatoms Combine with ions of opposite charge to form Combine with ions of opposite charge to form

ionic compoundsionic compounds Have both molecular and ionic characteristicsHave both molecular and ionic characteristics

Ex: NHEx: NH44++, NO, NO33

--, SO, SO442-2-

III. Polyatomic IonsAll but the ammonium ion are All but the ammonium ion are

negatively chargednegatively chargedMost are Most are oxyanions-oxyanions-

Polyatomic ions that contain Polyatomic ions that contain oxygenoxygen

III. Polyatomic Ions

Most commonMost common ion is given the ending ion is given the ending –ate–ate..

ClO3-

• chloratechlorate ClO2-

• chloritechlorite ClO-• hypochloritehypochloriteClO4

-• perchlorateperchlorate

• One less oxygenOne less oxygen than than –ate–ate ends inends in –ite–ite..• One less oxygenOne less oxygen than than –ite–ite is given the prefixis given the prefix

hypohypo..• One more oxygenOne more oxygen than than -ate-ate is given the prefixis given the prefix perper..

NO3-

• nitratenitrate NO2-

• nitritenitrite

Sample Problem 7-3

a. Write the formula for potassium sulfate.a. Write the formula for potassium sulfate.

b. Write the formula for calcium carbonate.b. Write the formula for calcium carbonate.

c. Write the formula for tin(IV) sulfate.c. Write the formula for tin(IV) sulfate.

potassium chloride

magnesium nitrate

copper(II) chloride

K+ Cl

Mg2+ NO3

Cu2+ Cl

KCl

Mg(NO3)2

CuCl2

Ionic Nomenclature Practice

NaBr

Na2CO3

FeCl3

sodium bromide

sodium carbonate

iron(III) chloride

Ionic Nomenclature Practice

pg. 235 #1-8 (all), 24-28(odd letters- a,c,e,g, etc.)Due: W 11/07

HomeworkHomework