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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
© 2009, Prentice-Hall, Inc.
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
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
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
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