Transcript

Chemical NomenclatureChemical Nomenclature

Octet RuleOctet Rule Atoms tend to achieve electron Atoms tend to achieve electron

configuration of Noble Gasesconfiguration of Noble Gases Octet = EightOctet = Eight Noble Gases have eight electrons in their Noble Gases have eight electrons in their

highest energy levelhighest energy level General Equation for Noble Gases is SGeneral Equation for Noble Gases is S22PP66

Atoms of Metallic Elements tend to lose Atoms of Metallic Elements tend to lose valence electron/s, leaving an octet in the valence electron/s, leaving an octet in the next lowest energy levelnext lowest energy level

Atoms of a Non-Metallic Element tend to Atoms of a Non-Metallic Element tend to gain a valence electron/s to achieve an gain a valence electron/s to achieve an OctetOctet

There are EXCEPTIONS to the Octet RuleThere are EXCEPTIONS to the Octet Rule

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Diatomic MoleculesDiatomic Molecules

These eight elements occur naturally as molecules These eight elements occur naturally as molecules containing two atoms.containing two atoms.

Astatine is considered a diatomicAstatine is considered a diatomic

IonsIons Atoms or groups of atoms with a chargeAtoms or groups of atoms with a charge Cations- positive ions - get by losing Cations- positive ions - get by losing

electrons(s)electrons(s) Anions- negative ions - get by gaining Anions- negative ions - get by gaining

electron(s)electron(s) Ionic bonding- held together by the Ionic bonding- held together by the

opposite chargesopposite charges Ionic solids are called saltsIonic solids are called salts

Even though atoms and cations have the Even though atoms and cations have the same name, there are many chemical same name, there are many chemical differences between metals and their differences between metals and their cations.cations.

Example:Example: Na Metal; reacts explosively in waterNa Metal; reacts explosively in water Na Cation; quite unreactiveNa Cation; quite unreactive

Cations Positive ions. Formed by losing electrons. More protons than electrons. Metals form cations.

K+1 Has lost one electron

Ca+2 Has lost two electrons

AnionAnion

A negative ion.A negative ion. Has gained electrons.Has gained electrons. Non metals can gain electrons.Non metals can gain electrons. Charge is written as a super script on the right.Charge is written as a super script on the right.

F-1 Has gained one electron

O-2 Has gained two electrons

Charges on ionsCharges on ions For most of the Group A elements, the For most of the Group A elements, the

Periodic Table can tell what kind of ion Periodic Table can tell what kind of ion they will form from their location.they will form from their location.

Elements in the same group have similar Elements in the same group have similar properties.properties.

Including the charge when they are ions.Including the charge when they are ions.

Monatomic Ions- consist of a single atom Monatomic Ions- consist of a single atom with a positive or negative charge resulting with a positive or negative charge resulting from the loss or gain of one or more valence from the loss or gain of one or more valence electronselectrons

Groups 1a, 2a, and 3a lose electrons and Groups 1a, 2a, and 3a lose electrons and form cationsform cations

Aluminum is the only common group 3a Aluminum is the only common group 3a element to lose electrons and form a cationelement to lose electrons and form a cation

Non-metals tend to gain electrons and form Non-metals tend to gain electrons and form an anion.an anion.

Groups 5a, 6a, and 7a form anionsGroups 5a, 6a, and 7a form anions In group 5a, there are three non-metals In group 5a, there are three non-metals

which form anionswhich form anions NN3-3-, P, P3-3-, & As, & As3-3-

Majority of elements in 4a & 0 do not form Majority of elements in 4a & 0 do not form ionsions

Group 0 rarely forms compoundsGroup 0 rarely forms compounds Ordinarily, two non-metals from group 4a, Ordinarily, two non-metals from group 4a,

C & Si are found in molecular compoundsC & Si are found in molecular compounds

+1+2 -1-2-3

LawsLaws Conservation of MassConservation of Mass Law of Definite Proportion-Law of Definite Proportion- compounds compounds

have a constant composition by mass.have a constant composition by mass. They react in specific ratios by mass.They react in specific ratios by mass. Multiple Proportions-Multiple Proportions- When two elements When two elements

form more than one compound, the ratios of form more than one compound, the ratios of the masses of the second element that the masses of the second element that combine with one gram of the first can be combine with one gram of the first can be reduced to small whole numbers.reduced to small whole numbers.

© 2009, Prentice-Hall, Inc.

Law of Constant CompositionLaw of Constant CompositionJoseph ProustJoseph Proust (1754 (1754––1826)1826)

This is also known as the law of definite This is also known as the law of definite proportions.proportions.

It states that the elemental composition of a It states that the elemental composition of a pure substance never varies.pure substance never varies.

© 2009, Prentice-Hall, Inc.

Law of Conservation of MassLaw of Conservation of Mass

The total mass of substances present at the The total mass of substances present at the end of a chemical process is the same as the end of a chemical process is the same as the mass of substances present before the mass of substances present before the process took place.process took place.

CompoundsCompounds Follow the Law of Definite Proportion.Follow the Law of Definite Proportion. Have a constant composition.Have a constant composition. Have to add the same number of atoms Have to add the same number of atoms

every time.every time. Two types.Two types.

Molecular CompoundsMolecular Compounds

Molecular compoundsMolecular compounds Made of molecules.Made of molecules. Made by joining nonmetal atoms together Made by joining nonmetal atoms together

into molecules.into molecules.

Ionic CompoundIonic CompoundIonic CompoundsIonic Compounds Made of cations and anions.Made of cations and anions. Metals and nonmetals.Metals and nonmetals. The electrons lost by the cation are gained The electrons lost by the cation are gained

by the anion.by the anion. The cation and anions surround each other.The cation and anions surround each other. Smallest piece is a Smallest piece is a FORMULA UNIT.FORMULA UNIT.

Formula UnitFormula Unit Formula Unit- lowest whole-number ratio Formula Unit- lowest whole-number ratio

of the ions in the compoundof the ions in the compound ExampleExample NaNa++ClCl- -

Ratio is 1:1 Ratio is 1:1 The formula unit is NaClThe formula unit is NaCl

Formula UnitFormula Unit The smallest whole number ratio of The smallest whole number ratio of

atoms in an ionic compound.atoms in an ionic compound. Ions surround each other so you can’t Ions surround each other so you can’t

say which is hooked to which. say which is hooked to which.

Two Types of CompoundsTwo Types of Compounds

Smallest piece

Melting Point

State

Types of elements

Formula Unit Molecule

Metal and Nonmetal

Nonmetals

solid liquid or gas

High >300ºC Low <300ºC

Ionic Molecular

© 2009, Prentice-Hall, Inc.

Types of FormulasTypes of Formulas Empirical formulas give the lowest whole-Empirical formulas give the lowest whole-

number ratio of atoms of each element in a number ratio of atoms of each element in a compound.compound.

Molecular formulas give the exact number Molecular formulas give the exact number of atoms of each element in a compound.of atoms of each element in a compound.

Writing FormulasWriting Formulas Two sets of rules, ionic and covalentTwo sets of rules, ionic and covalent To decide which to use, decide what the To decide which to use, decide what the

first word is.first word is. If is a metal or polyatomic use ionic.If is a metal or polyatomic use ionic. If it is a non-metal use covalentIf it is a non-metal use covalent

© 2009, Prentice-Hall, Inc.

Writing FormulasWriting Formulas

Because compounds are electrically neutral, one Because compounds are electrically neutral, one can determine the formula of a compound this can determine the formula of a compound this way:way:– The charge on the cation becomes the subscript on the The charge on the cation becomes the subscript on the

anion.anion.

– The charge on the anion becomes the subscript on the The charge on the anion becomes the subscript on the cation.cation.

– If these subscripts are not in the lowest whole-number If these subscripts are not in the lowest whole-number ratio, divide them by the greatest common factor.ratio, divide them by the greatest common factor.

Ionic FormulasIonic Formulas Charges must add up to zeroCharges must add up to zero get charges from table, name of metal ion, get charges from table, name of metal ion,

or memorized from the listor memorized from the list use parenthesis to indicate multiple use parenthesis to indicate multiple

polyatomicspolyatomics

Ionic FormulasIonic Formulas Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 nitride - ide tells you it comes from the nitride - ide tells you it comes from the

tabletable nitride is Nnitride is N-3-3

Ionic FormulasIonic Formulas Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 nitride - ide tells you it comes from the tablenitride - ide tells you it comes from the table nitride is Nnitride is N-3-3 doesn’t add up to zerodoesn’t add up to zero

Na+1 N-3

Ionic FormulasIonic Formulas Sodium nitrideSodium nitride sodium- Na is always +1sodium- Na is always +1 nitride - ide tells you it comes from the tablenitride - ide tells you it comes from the table nitride is Nnitride is N-3-3 doesn’t add up to zerodoesn’t add up to zero Need 3 NaNeed 3 Na

Na+1 N-3 Na3N

Writing FormulasWriting Formulas Write the formula for calcium chloride.Write the formula for calcium chloride. Calcium is CaCalcium is Ca+2+2 Chloride is ClChloride is Cl-1-1 CaCa+2+2 Cl Cl-1-1 would have a +1 charge. would have a +1 charge. Need another Need another ClCl-1-1 CaCa+2+2 Cl Cl22

-1-1

CrisscrossCrisscross

Switch the numerical value of the chargesSwitch the numerical value of the charges

Ba2+ N3-2 3

Ba3 N2• Reduce ratio if possible

Polyatomic IonsPolyatomic Ions Polyatomic Ion- Tightly bound groups of Polyatomic Ion- Tightly bound groups of

atoms that behave as a unit and carry a atoms that behave as a unit and carry a chargecharge

Unlike monatomic ions; Sulfate anion is Unlike monatomic ions; Sulfate anion is composed of 1 Sulfur atom and 4 oxygen composed of 1 Sulfur atom and 4 oxygen atomsatoms

These five atoms form a Sulfate AnionThese five atoms form a Sulfate Anion It has a –2 charge an is written SOIt has a –2 charge an is written SO44

2-2-

Polyatomic anions either end in ITE or ATEPolyatomic anions either end in ITE or ATE Out of the two similar polyatomic ions, the Out of the two similar polyatomic ions, the

polyatomic with less Oxygens ends in itepolyatomic with less Oxygens ends in ite Example: Example: Sulfite and SulfateSulfite and Sulfate Sulfite; SOSulfite; SO33

2-2-

Sulfate; SOSulfate; SO442-2-

There are three exceptions to the There are three exceptions to the Polyatomic RulePolyatomic Rule

1) Ammonium NH1) Ammonium NH44+ + ---- The only positive ---- The only positive

polyatomic ionpolyatomic ion 2) Cyanide CN2) Cyanide CN- ---- - ---- Ends in IDEEnds in IDE 3) Hydroxide OH3) Hydroxide OH-- --- Ends in IDE --- Ends in IDE

Write the formulas for theseWrite the formulas for these Lithium sulfideLithium sulfide tin (II) oxidetin (II) oxide tin (IV) oxidetin (IV) oxide Magnesium fluorideMagnesium fluoride Copper (II) sulfateCopper (II) sulfate Iron (III) phosphideIron (III) phosphide gallium nitrategallium nitrate Iron (III) sulfideIron (III) sulfide

Ionic CompoundsIonic Compounds Sodium sulfiteSodium sulfite calcium iodidecalcium iodide Lead (II) oxide Lead (II) oxide Lead (IV) oxideLead (IV) oxide Mercury (I) sulfideMercury (I) sulfide Barium chromateBarium chromate Aluminum hydrogen sulfateAluminum hydrogen sulfate Cerium (IV) nitriteCerium (IV) nitrite

Write the formulas for theseWrite the formulas for these Ammonium chlorideAmmonium chloride ammonium sulfideammonium sulfide barium nitratebarium nitrate

Naming compoundsNaming compounds Two typesTwo types IonicIonic - metal and non metal or polyatomics - metal and non metal or polyatomics CovalentCovalent- we will just learn the rules for 2 - we will just learn the rules for 2

non-metalsnon-metals

There are two methods for naming cations There are two methods for naming cations with multiple chargeswith multiple charges

The Stock System and Classical SystemThe Stock System and Classical System The Stock system is the preferred methodThe Stock system is the preferred method

Stock SystemStock System The stock system uses roman numerals in The stock system uses roman numerals in ( ). The ( ) indicate the numerical charge of the ( ). The ( ) indicate the numerical charge of the

cation.cation.Example:Example:FeFe2+ 2+ Name: Iron(II)Name: Iron(II)There is no space between the name and the There is no space between the name and the

parenthesis parenthesis Example:Example:CuCu1+ 1+ Name: Name: Copper(1)Copper(1)

Classical SystemClassical System The classical system uses the root word The classical system uses the root word

with different suffixes as the end of the with different suffixes as the end of the wordword

OUS- is used to name the cation with the OUS- is used to name the cation with the lower of the two ionic chargeslower of the two ionic charges

IC- is used to name the cation with the IC- is used to name the cation with the higher of the two ionic chargeshigher of the two ionic charges

Example:Example: FeFe2+2+ and Fe and Fe3+3+

Name: FerrousName: Ferrous Name: Ferric Name: Ferric What is the problem with the classical What is the problem with the classical

system?system?

The classical system does not tell you the The classical system does not tell you the charge of the ion.charge of the ion.

The name only tells you which cation is The name only tells you which cation is either larger or smaller out of the paireither larger or smaller out of the pair

Few transition metals have only one ionic Few transition metals have only one ionic chargecharge

These three elements don’t have roman These three elements don’t have roman numerals next to there namenumerals next to there name

Exceptions:Exceptions: AgAg++

CdCd2+2+

ZnZn2+2+

Ionic compoundsIonic compounds If the cation is monoatomic- Name the If the cation is monoatomic- Name the

metal (cation) just write the name.metal (cation) just write the name. If the cation is polyatomic- name itIf the cation is polyatomic- name it If the anion is monoatomic- name it but If the anion is monoatomic- name it but

change the ending to change the ending to -ide-ide If the anion is poly atomic- just name itIf the anion is poly atomic- just name it practicepractice

Naming Binary Ionic CompoundsNaming Binary Ionic Compounds

Write the name of CuOWrite the name of CuO Need the charge of CuNeed the charge of Cu O is -2O is -2 copper must be +2copper must be +2 Copper (II) chlorideCopper (II) chloride Name CoClName CoCl33

Cl is -1 and there are three of them = -3Cl is -1 and there are three of them = -3 Co must be +3 Cobalt (III) chlorideCo must be +3 Cobalt (III) chloride

Naming Binary Ionic CompoundsNaming Binary Ionic Compounds

Write the name of CuWrite the name of Cu22S.S. Since S is -2, the CuSince S is -2, the Cu22 must be +2, so each must be +2, so each

one is +1.one is +1. copper (I) sulfidecopper (I) sulfide FeFe22OO33 Each O is -2 3 x -2 = -6Each O is -2 3 x -2 = -6 3 Fe must = +6, so each is +2.3 Fe must = +6, so each is +2. iron (III) oxide iron (III) oxide

Ternary Ionic Compounds Ternary Ionic Compounds Will have polyatomic ions Will have polyatomic ions At least three elements (3 capital letters)At least three elements (3 capital letters) Still just name the ionsStill just name the ions

NaNONaNO33

CaSOCaSO44

CuSOCuSO33

Ternary Ionic CompoundsTernary Ionic Compounds LiCNLiCN Fe(OH)Fe(OH)33

(NH(NH44))22COCO33

NiPONiPO44

Ionic CompoundsIonic Compounds Have to know what ions they formHave to know what ions they form off table, polyatomic, or figure it outoff table, polyatomic, or figure it out CaSCaS KK22SS

AlPOAlPO44

KK22SOSO44

FeSFeS CoICoI33

Ionic CompoundsIonic Compounds FeFe22(C(C22OO44))

MgOMgO MnOMnO

KMnOKMnO44

NHNH44NONO33

HgHg22ClCl22

CrCr22OO33

Ionic CompoundsIonic Compounds KClOKClO44

NaClONaClO33

YBrOYBrO22

Cr(ClO)Cr(ClO)66

Molecular CompoundsMolecular Compounds

Writing names and FormulasWriting names and Formulas

Molecules & Molecular CompoundsMolecules & Molecular Compounds

Elements are the building materials of the Elements are the building materials of the substances that make up all living and substances that make up all living and nonliving thingsnonliving things

Only about 100 elements but there are Only about 100 elements but there are millions of different compounds made from millions of different compounds made from their atomstheir atoms

Thus, naming compounds is an essential Thus, naming compounds is an essential skill in chemistry skill in chemistry

In nature, only Noble Gases tend to exist as In nature, only Noble Gases tend to exist as isolated atoms.isolated atoms.

They are monatomic; that is, they consist of single They are monatomic; that is, they consist of single atomsatoms

Many elements found in nature are in the form of Many elements found in nature are in the form of moleculesmolecules

Molecule- is the smallest electrically neutral unit Molecule- is the smallest electrically neutral unit of a substance that still has the properties of the of a substance that still has the properties of the substancesubstance

Molecules are made up of two or more atoms that Molecules are made up of two or more atoms that act as a unitact as a unit

Atoms of different elements may combine Atoms of different elements may combine chemically to form compoundschemically to form compounds

In many compounds, the atoms combine to form In many compounds, the atoms combine to form molecules.molecules.

Molecular Compounds- Compounds composed of Molecular Compounds- Compounds composed of moleculesmolecules

Molecular Compounds tend to have relativity low Molecular Compounds tend to have relativity low melting and boiling pointsmelting and boiling points

Many of these compounds thus exist as gases or Many of these compounds thus exist as gases or liquids at room temperature.liquids at room temperature.

Molecular compoundsMolecular compounds made of just nonmetalsmade of just nonmetals smallest piece is a moleculesmallest piece is a molecule can’t be held together because of opposite can’t be held together because of opposite

charges.charges. can’t use charges to figure out how many of can’t use charges to figure out how many of

each atomeach atom

Naming Covalent CompoundsNaming Covalent Compounds Two words, with prefixesTwo words, with prefixes Prefixes tell you how many.Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, mono, di, tri, tetra, penta, hexa, septa, nona,

decadeca First element whole name with the First element whole name with the

appropriate prefix, except monoappropriate prefix, except mono Second element, Second element, -ide -ide ending with appropriate ending with appropriate

prefixprefix PracticePractice

© 2009, Prentice-Hall, Inc.

Nomenclature of Binary Nomenclature of Binary CompoundsCompounds

The less electronegative The less electronegative atom is usually listed first. atom is usually listed first.

A prefix is used to denote A prefix is used to denote the number of atoms of each the number of atoms of each element in the compound element in the compound ((monomono- is not used on the - is not used on the first element listed, first element listed, however) .however) .

© 2009, Prentice-Hall, Inc.

Nomenclature of Binary Nomenclature of Binary CompoundsCompounds

The ending on the more The ending on the more electronegative element is electronegative element is changed to -changed to -ideide..

– COCO22: carbon dioxide: carbon dioxide– CClCCl44: carbon tetrachloride: carbon tetrachloride

© 2009, Prentice-Hall, Inc.

Nomenclature of Binary Nomenclature of Binary CompoundsCompounds

If the prefix ends with If the prefix ends with aa or or oo and the name of the and the name of the element begins with a element begins with a vowel, the two successive vowel, the two successive vowels are often elided into vowels are often elided into one.one.

NN22OO55: dinitrogen pentoxide: dinitrogen pentoxide

COCO22

CO CO CClCCl44

NN22OO44

XeFXeF66

NN44OO44

PP22OO1010

Naming Covalent CompoundsNaming Covalent Compounds

Name TheseName These NN22OO

NONO22

ClCl22OO77

CBrCBr44

COCO22

BaClBaCl22

Covalent compoundsCovalent compounds The name tells you how to write the The name tells you how to write the

formulaformula duhduh Sulfur dioxideSulfur dioxide diflourine monoxidediflourine monoxide nitrogen trichloridenitrogen trichloride diphosphorus pentoxidediphosphorus pentoxide

Write formulas for theseWrite formulas for these diphosphorus pentoxidediphosphorus pentoxide tetraiodide nonoxidetetraiodide nonoxide sulfur hexaflouridesulfur hexaflouride nitrogen trioxidenitrogen trioxide Carbon tetrahydrideCarbon tetrahydride phosphorus trifluoridephosphorus trifluoride aluminum chloridealuminum chloride


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