naming compounds powerpoint

Chemistry: Atoms FirstJulia Burdge & Jason Overby

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Chapter 5

Naming Ionic and Covalent Compounds

Kent L. McCorkle

Cosumnes River College

Sacramento, CA

Homework: Chapter 5. 23, 25, 27,55, 61, 63, 99 and 111

A compound is a substance composed of two or more elements combined in a specific ratio and held together by chemical bonds.

Familiar examples of compounds are water and salt (sodium chloride).

CompoundsCompounds5.1

Ionic Compounds and BondingIonic Compounds and Bonding

The resulting electrically neutral compound, sodium chloride, is represented with the chemical formula NaCl.

The chemical formula, or simply formula, of an ionic compound denotes the constituent elements and the ratio in which they combine.

A monatomic ion is named by changing the ending of the element’s name to –ide.

Cl– is chloride O2– is oxide

Some metals can form cations of more than one possible charge.

Fe2+ : ferrous ion [Fe(II)]Fe3+ : ferric ion [Fe(III)]

Mn2+ : manganese(II) ionMn3+ : manganese(III) ionMn4+ : manganese(IV) ion

Naming Ions and Ionic CompoundsNaming Ions and Ionic Compounds5.4

Naming Ions and Ionic CompoundsNaming Ions and Ionic Compounds

Naming Ions and Ionic CompoundsNaming Ions and Ionic Compounds

Formulas for ionic compounds are generally empirical formulas.

Ionic compounds are electronically neutral.

Al3+ O2–

Al2O3

In order for ionic compounds to be electronically neutral, the sum of the charges on the cation and anion in each formula must be zero.

Aluminum oxide:

Sum of charges: 2(+3) + 3(–2) = 0

Formulas of Ionic CompoundsFormulas of Ionic Compounds

Formulas of Ionic CompoundsFormulas of Ionic Compounds

Naming Ions and Ionic CompoundsNaming Ions and Ionic Compounds

To name ionic compounds:

1) Name the cation omit the word ionuse a Roman numeral if the cation can have more than one charge

2) Name the anionomit the word ion

Examples:NaCN sodium cyanideFeCl2 iron(II) chlorideFeCl3 iron(III) chloride

Polyatomic ions consist of a combination of two or more atoms.

Formulas are determined following the same rule as for ionic compounds containing only monatomic ions: ions must combine in a ratio that give a neutral formula overall.

Calcium phosphate:

Covalent Bonding in Ionic SpeciesCovalent Bonding in Ionic Species5.7

Ca2+ PO43–

Ca3(PO4)2

Sum of charges: 3(+2) + 2(–3) = 0

Covalent Bonding in Ionic SpeciesCovalent Bonding in Ionic Species

Covalent Bonding in Ionic SpeciesCovalent Bonding in Ionic Species

Worked Example 5.9

Strategy Begin by identifying the cation and anion in each compound, and then combine the names for each, eliminating the word ion.

Name the following ionic compounds: (a) Fe2(SO4)3, (b) Al(OH)3, and (c) Hg2O.

Solution (a) Fe2(SO4)3 is iron(III) sulfate.

(b) Al(OH)3 is aluminum hydroxide.

(c) Hg2O is mercury(I) oxide.

Think About It Be careful not to confuse the subscript in the formula with the charge in the metal ion. In part (a), for example, the subscript on Fe is 2, but this is an iron(III) compound.

Covalent Bonding in Ionic SpeciesCovalent Bonding in Ionic Species

Oxoanions are polyatomic anions that contain one or more oxygen atoms and one atom (the “central atom”) of another element.

Starting with the oxoanions that end in –ate, we can name these ions as follows:1)The ion with one more O atom than the –ate ion is called the per…ate ion. Thus, ClO3

- is the chlorate ion, so ClO4- is the

perchlorate ion.2)The ion with one less O atom than the –ate ion is called the –ite ion. Thus, ClO2

- is the chlorite ion.3)The ion with two fewer O atom than the –ate ion is called the hypo…ite ion. Thus, ClO- is the hypochlorite ion.

At minimum, memorize the oxoanions that end in –ate so you can apply these guidelines when necessary.

Covalent Bonding in Ionic SpeciesCovalent Bonding in Ionic Species

perchlorate ClO4-

chlorate ClO3-

chlorite ClO2-

hypochlorite ClO-

nitrate NO3-

nitrite NO2-

phosphate PO43-

phosphite PO33-

sulfate SO42-

sulfite SO32-

Worked Example 5.10

Strategy Each species is either an oxoanion or an oxoacid. Identify the “reference oxidation” (the one with the –ate ending) for each, and apply the rules to determine appropriate names.

Name the following species: (a) BrO4-, (b) HCO3

-, and (c) H2CO3.

Solution (a) BrO4- has one more O atom than the bromate ion (BrO3

-), so BrO4-

is the perbromate ion.

(b) CO32- is the carbonate ion. Because HCO3

- has one ionizable hydrogen atom, it is called the hydrogen carbonate ion.

(c) With two ionizable hydrogen atoms and no charge on the compound, H2CO3 is carbonic acid.Think About It Make sure that the charges sum to zero in each compound formula. In part (a), for example, Hg2+ + 2Cl- = (+2) + 2(-1) = 0; in part (b), (+2) + 2(-1) = 0; and in part (c), 3(+1) + (-3) = 0.

Think About It Remembering all these names and formulas is greatly facilitated by memorizing the common ions that end in –ate.

chlorate ClO3- nitrate

NO3-

iodate IO3-

carbonate CO32-

bromate BrO3- oxalate

C2O42-

sulfate SO42- chromate

CrO42-

phosphate PO43- permanganate

MnO4-

Worked Example 5.11

Strategy The –ous ending in the name of an acid indicates that the acid is derived from an oxoanion ending in –ite. The oxoanion must be sulfite, SO3

2-, so add enough hydrogen ions to make a neutral formula.

Determine the formula of sulfurous acid.

Solution The formula of sulfurous acid is H2SO3.

Think About It Remembering all these names and formulas is greatly facilitated by memorizing the common ions that end in -ate.

HydratesHydrates

A hydrate is a compound that has a specific number of water molecules within its solid structure.

For example, in its normal state, copper(II) sulfate has five water molecules associated with it.

Systematic name: copper(II) sulfate pentahydrateFormula: Cu(SO)4 ∙ 5H2O

Some other hydrates areBaCl2 ∙ 2H2OLiCl ∙ H2OMgSO4 ∙ 7H2OSr(NO3)2 ∙ 4H2O

HydratesHydrates

When the water molecules are driven off by heating, the resulting compound, Cu(SO)4, is sometimes called anhydrous copper(II) sulfate.

Anhydrous means the compound no longer has water molecules associated with it.

Familiar Inorganic CompoundsFamiliar Inorganic Compounds

Covalent Bonding and MoleculesCovalent Bonding and Molecules

A chemical formula denotes the composition of the substance.

A molecular formula shows the exact number of atoms of each element in a molecule.

Some elements have two or more distinct forms known as allotropes.For example, oxygen (O2) and ozone (O3) are allotropes of oxygen.

A structural formula shows not only the elemental composition, but also the general arrangements.

Covalent Bonding and MoleculesCovalent Bonding and Molecules

Molecular substances can also be represented using empirical formulas, the whole-number ratio of elements.

While, the molecular formulas tell us the actual number of atoms (the true formula), the empirical formula gives the simplest formula.

Molecular formula: N2H4

Empirical formula: NH2

The molecular and empirical formulas are often the same.

Covalent Bonding and MoleculesCovalent Bonding and Molecules

Covalent Bonding and MoleculesCovalent Bonding and Molecules

Remember that binary molecular compounds are substances that consist of just two different elements.

Nomenclature:1) Name the first element that appears in the formula.

2) Name the second element that appears in the formula, changing its ending to –ide.

Examples:HCl hydrogen chloride

HI hydrogen iodide

Naming Molecular CompoundsNaming Molecular Compounds5.6

Greek prefixes are used to denote the number of atoms of each element present.

Naming Molecular CompoundsNaming Molecular Compounds

The prefix mono- is generally omitted for the first element.

For ease of pronunciation, we usually eliminate the last letter of a prefix that ends in “o” or “a” when naming an oxide.

Example: N2O5 is dinitrogen pentoxide not dinitrogen pentaoxide

Naming Molecular CompoundsNaming Molecular Compounds

Worked Example 5.7

Strategy Each compound will be named using the systematic nomenclature including, where necessary, appropriate Greek prefixes.

Name the following binary molecular compounds: (a) NF3 and (b) N2O4.

Solution (a) nitrogen trifluoride

(b) dinitrogen tetroxide

Think About It Make sure that the prefixes match the subscripts in the molecular formulas and that the word oxide is not preceded immediately by an “a” or an “o”.

Worked Example 5.8

Strategy The formula for each compound will be deduced using the systematic nomenclature guidelines.

Write the chemical formulas for the following binary molecular compounds: (a) sulfur tetrafluoride and (b) tetraphosphorus decasulfide.

Solution (a) SF4

(b) P4S10

Think About It Double-check that the subscripts in the formulas match the prefixes in the compound names: (a) 4 = tetra and (b) 4 = tetra and 10 = deca.

The names of molecular compounds containing hydrogen do not usually conform to the systematic nomenclature guidelines.

Many are called by the common, nonsystematic names or by names that do not indicate explicitly the number of H atoms present.

Examples:B2H6 DiboraneSiH4 SilaneNH3 AmmoniaPH3 PhosphineH2O WaterH2S Hydrogen sulfide

Compounds Containing HydrogenCompounds Containing Hydrogen

Compounds Containing HydrogenCompounds Containing Hydrogen

One definition of an acid is a substance that produces hydrogen ions (H+) when dissolved in water.

HCl is an example of a binary compound that is an acid when dissolved in water.

To name these types of acids:

1) remove the –gen ending from hydrogen

2) change the –ide ending on the second element to –ic.

hydrogen chloride → hydrochloric acid

Compounds Containing HydrogenCompounds Containing Hydrogen

A compound must contain at least one ionizable hydrogen atom to be an acid upon dissolving.

Our nomenclature discussion so far has focused on inorganic compounds, generally defined as those without carbon.

Organic compounds contain carbon and hydrogen, sometimes in combination with other atoms.

Hydrocarbons contain only carbon and hydrogen.

The simplest hydrocarbons are called alkanes.

Organic CompoundsOrganic Compounds

Organic CompoundsOrganic Compounds

Organic CompoundsOrganic Compounds

Organic CompoundsOrganic Compounds

Many organic compounds contain groups of atoms known as functional groups, which often determine a molecule’s reactivity.

A molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds

H2 H2O NH3 CH4

A diatomic molecule contains only two atomsH2, N2, O2, Br2, HCl, CO

A polyatomic molecule contains more than two atomsO3, H2O, NH3, CH4

Writing Chemical Formals

One way to remember these elements is:

Mr. BrINClHOF

There are 7 elements that occur in nature as a diatomic molecule

A monatomic ion contains only one atom

A polyatomic ion contains more than one atom

Na+, Cl-, Ca2+, O2-, Al3+, N3-

OH-, CN-, NH4+, NO3

-

2.5

Guidelines for Writing Chemical Formulasfor Binary Compounds

1. Except for Hydrogen, the element farther to the left in theperiodic table appears first. Ie: KCl, PCl3, Al2S3, and Fe3O4

2. If hydrogen is present, it appears last except when the otherelement is from group 16 or 17. Ie: LiH, NH3, B2H6, CH4

H2O, HCl and HI

3. If both elements are from the same group, the lower oneappears first. Ie: SiC and BrF3

A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance

An empirical formula shows the simplest whole-number ratio of the atoms in a substance

H2OH2O

molecular empirical

C6H12O6 CH2O

O3 O

N2H4 NH2

ionic compounds consist of a combination of cations and an anions• the formula is always the same as the empirical formula

• the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero

The ionic compound NaCl

Formula of Ionic Compounds

Al2O3

2 x +3 = +6 3 x -2 = -6

Al3+ O2-

CaBr2

1 x +2 = +2 2 x -1 = -2

Ca2+ Br-

Na2CO3

1 x +2 = +2 1 x -2 = -2

Na+ CO32-

M

U

S

T

K

N

O

W

Ion Name (common name) Ion Name (Common name)

NH4+ Ammonium CO3

2- Carbonate

H3O+ Hydronium HCO3- Hydrogen carbonate

(bicarbonate)OH- Hydroxide SO3

2- Sulfite

CN- Cyanide HSO3- Hydrogen sulfite

NO2- Nitrite SO4

2- Sulfate

NO3- Nitrate HSO4

- Hydrogen sulfate

ClO- Hypochlorite (often written OCl-)

SCN- Thiocyanate

ClO2- Chlorite S2O3

2- Thiosulfate

ClO3- Chlorate CrO4

2- Chromate

ClO4- Perchlorate Cr2O7

2- Dichromate

MnO4- Permanganate PO4

3- Phosphate

CH3CO2-

Acetate (can be written C2H3O2

-)HPO4

2- Hydrogen phosphate

C2O42- Oxalate H2PO4

- Dihydrogen phospate

Recognizing Ionic Compounds

A compound is ionic if it contains a metal from group 1Or group 2 or one of the polyatomic ions. Binary metal Oxides and sulfides also have ionic character

Fig 2-23Pg 59

Pure water(left) and a solution of sugar(right) do not conduct electricitybecause they contain virtually no ions. Asolution of salt (center) conducts electricity wellbecause it contain mobile cations and anions.Courtesy Ken Karp

Chemical Nomenclature• Ionic Compounds

– often a metal + nonmetal– anion (nonmetal), add “ide” to element name

BaCl2 barium chloride

K2O potassium oxide

Mg(OH)2 magnesium hydroxide

KNO3 potassium nitrate

Cations of Variable Charge

Transition metals such as copper may form cationsOf different charge. This is represented by placing aRoman numeral after the transition metal in Parentheses after the name of the metal.

CuO Copper(II) oxideCu2O Copper(I) oxide

• Transition metal ionic compounds– indicate charge on metal with Roman numerals

FeCl2 2 Cl- -2 so Fe is +2 iron(II) chloride

FeCl3 3 Cl- -3 so Fe is +3 iron(III) chloride

Cr2S3 3 S-2 -6 so Cr is +3 (6/2) chromium(III) sulfide

• Molecular compounds• nonmetals or nonmetals + metalloids• common names

• H2O, NH3, CH4, C60

• element further left in periodic table is 1st

• element closest to bottom of group is 1st

• if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom

• last element ends in ide

HI hydrogen iodide

NF3 nitrogen trifluoride

SO2 sulfur dioxide

N2Cl4 dinitrogen tetrachloride

NO2 nitrogen dioxide

N2O dinitrogen monoxide

Molecular Compounds

TOXIC!

Laughing Gas

An acid can be defined as a substance that yields hydrogen ions (H+) when dissolved in water.

HCl•Pure substance, hydrogen chloride•Dissolved in water (H+ Cl-), hydrochloric acid

An oxoacid is an acid that contains hydrogen, oxygen, and another element.

HNO3 nitric acid

H2CO3 carbonic acid

H2SO4 sulfuric acidHNO3

A base can be defined as a substance that yields hydroxide ions (OH-) when dissolved in water.

NaOH sodium hydroxide

KOH potassium hydroxide

Ba(OH)2 barium hydroxide

Hydrates

A hydrate is an ionic compound that has water moleculesIncorporated into their solid structures

Writing the formula: name of ionic compound-# H2O

Pg 89

The Hydrate of coppersulfate is the pentahydrate,and the anhydrous coppersulfate will absorb water to form the Hydrate.

CuSO4 5 H2O.Copper(II)sulfate.pentahydrate

Olmsted Williams

Writing Chemical Formulas For non ionic compounds with more than 2 atoms

Write Carbon first

Hydrogen second

All other elements in alphabetical order

4 Hydrogen2 Carbons4 oxygens1 Fluorine1 Sulfur

C2H4FlO4S

4 Carbons1 Bromine8 Hydrogen1 Chlorine2 Nitrogen4 Oxygens

C4H8BrClN2O4

Let’s try some………………

4 Iodines6 Carbons10 Hydrogens

C6H10I4

Structural Formulas for Carbon Containing Compounds

Draw a line to show a connection between all elements in a molecule

Carbon makes 4 connections (this makes them central or inside atoms)Oxygen and Sulfur make 2Halogens and Hydrogen make 1 (terminal atoms)Nitrogen makes 3

Let’s try some…………………

C2H5FlO (This molecule contains an alcohol (OH)

H-C-C-O-HFl

H

H

H

C4H7ClN (This molecule containsAn amine, NH2)

Cl-C-C-C-C-NHH

H

H H

H

H

HH H

Line Formulas for Carbon Containing Compounds

All ends and corners represent a CarbonHydrogens on Carbons are NOT shownAll other elements and Hydrogens not on a Carbon are shown

Let’s try some…………………(It always helps to draw the structural formula first)

C2H5FlO (This molecule contains an alcohol (OH)

H-C-C-O-HFl

H

H

H

C4H7ClN (This molecule containsAn amine, NH2)

Cl-C-C-C-C-NHH

H

H H

H

H

HH H

F

O HCl

NH

H

Naming Carbon Compounds

Prefixes for number of carbons

1 Meth-2 Eth-

3 Prop-4 But-

5 Pent-6 Hex-7 Hept-8 Oxt-9 Non-10 Dec-

If there are only single bondsThe ending is ane

Hydrogens are understood

All other groups attached to a carbon are listed before the carbon based name

If the compound is circular the Prefix cyclo is attached

If there is an –OH group attachedThe compound ends in ol

Let’s try some problems……………………….