Chemical Nomenclature

Octet RuleAtoms tend to achieve electron configuration of Noble GasesOctet = EightNoble Gases have eight electrons in their highest energy levelGeneral Equation for Noble Gases is S2P6

Atoms of Metallic Elements tend to lose valence electron/s, leaving an octet in the next lowest energy levelAtoms of a Non-Metallic Element tend to gain a valence electron/s to achieve an OctetThere are EXCEPTIONS to the Octet Rule

2009, Prentice-Hall, Inc.Diatomic MoleculesThese eight elements occur naturally as molecules containing two atoms.Astatine is considered a diatomic

IonsAtoms or groups of atoms with a chargeCations- positive ions - get by losing electrons(s)Anions- negative ions - get by gaining electron(s)Ionic bonding- held together by the opposite chargesIonic solids are called salts

Even though atoms and cations have the same name, there are many chemical differences between metals and their cations.Example:Na Metal; reacts explosively in waterNa Cation; quite unreactive

CationsPositive ions.Formed by losing electrons.More protons than electrons.Metals form cations.K+1Has lost one electronCa+2Has lost two electrons

AnionA negative ion.Has gained electrons.Non metals can gain electrons.Charge is written as a super script on the right.F-1Has gained one electronO-2Has gained two electrons

Charges on ionsFor most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location.Elements in the same group have similar properties.Including the charge when they are ions.

Monatomic Ions- consist of a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electronsGroups 1a, 2a, and 3a lose electrons and form cationsAluminum is the only common group 3a element to lose electrons and form a cation

Non-metals tend to gain electrons and form an anion.Groups 5a, 6a, and 7a form anionsIn group 5a, there are three non-metals which form anionsN3-, P3-, & As3-

Majority of elements in 4a & 0 do not form ionsGroup 0 rarely forms compoundsOrdinarily, two non-metals from group 4a, C & Si are found in molecular compounds

+1+2-1-2-3

LawsConservation of MassLaw of Definite Proportion- compounds have a constant composition by mass.They react in specific ratios by mass.Multiple Proportions- When two elements form more than one compound, the ratios of the masses of the second element that combine with one gram of the first can be reduced to small whole numbers.

2009, Prentice-Hall, Inc.Law of Constant CompositionJoseph Proust (17541826)This is also known as the law of definite proportions.It states that the elemental composition of a pure substance never varies.

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2009, Prentice-Hall, Inc.Law of Conservation of MassThe total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place.

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CompoundsFollow the Law of Definite Proportion.Have a constant composition.Have to add the same number of atoms every time.Two types.

Molecular CompoundsMolecular compoundsMade of molecules.Made by joining nonmetal atoms together into molecules.

Ionic CompoundIonic CompoundsMade of cations and anions.Metals and nonmetals.The electrons lost by the cation are gained by the anion.The cation and anions surround each other.Smallest piece is a FORMULA UNIT.

Formula UnitFormula Unit- lowest whole-number ratio of the ions in the compoundExampleNa+Cl- Ratio is 1:1 The formula unit is NaCl

Formula UnitThe smallest whole number ratio of atoms in an ionic compound.Ions surround each other so you cant say which is hooked to which.

Two Types of CompoundsSmallest pieceMelting PointStateTypes of elementsFormula UnitMoleculeMetal and NonmetalNonmetalssolid liquid or gasHigh >300CLow

2009, Prentice-Hall, Inc.Types of FormulasEmpirical formulas give the lowest whole-number ratio of atoms of each element in a compound.Molecular formulas give the exact number of atoms of each element in a compound.

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Writing FormulasTwo sets of rules, ionic and covalentTo decide which to use, decide what the first word is.If is a metal or polyatomic use ionic.If it is a non-metal use covalent

2009, Prentice-Hall, Inc.Writing FormulasBecause compounds are electrically neutral, one can determine the formula of a compound this way:The charge on the cation becomes the subscript on the anion.The charge on the anion becomes the subscript on the cation.If these subscripts are not in the lowest whole-number ratio, divide them by the greatest common factor.

Ionic FormulasCharges must add up to zeroget charges from table, name of metal ion, or memorized from the listuse parenthesis to indicate multiple polyatomics

Ionic FormulasSodium nitridesodium- Na is always +1nitride - ide tells you it comes from the tablenitride is N-3

Ionic FormulasSodium nitridesodium- Na is always +1nitride - ide tells you it comes from the tablenitride is N-3 doesnt add up to zeroNa+1N-3

Ionic FormulasSodium nitridesodium- Na is always +1nitride - ide tells you it comes from the tablenitride is N-3 doesnt add up to zeroNeed 3 NaNa+1N-3Na3N

Writing FormulasWrite the formula for calcium chloride.Calcium is Ca+2 Chloride is Cl-1 Ca+2 Cl-1 would have a +1 charge.Need another Cl-1 Ca+2 Cl2-1

CrisscrossSwitch the numerical value of the chargesBa2+N3-23Ba3N2Reduce ratio if possible

Polyatomic IonsPolyatomic Ion- Tightly bound groups of atoms that behave as a unit and carry a chargeUnlike monatomic ions; Sulfate anion is composed of 1 Sulfur atom and 4 oxygen atomsThese five atoms form a Sulfate AnionIt has a 2 charge an is written SO42-

Polyatomic anions either end in ITE or ATEOut of the two similar polyatomic ions, the polyatomic with less Oxygens ends in iteExample: Sulfite and SulfateSulfite; SO32-Sulfate; SO42-

There are three exceptions to the Polyatomic Rule1) Ammonium NH4+ ---- The only positive polyatomic ion2) Cyanide CN- ---- Ends in IDE3) Hydroxide OH- --- Ends in IDE

Write the formulas for theseLithium sulfidetin (II) oxidetin (IV) oxideMagnesium fluorideCopper (II) sulfateIron (III) phosphidegallium nitrateIron (III) sulfide

Ionic CompoundsSodium sulfitecalcium iodideLead (II) oxide Lead (IV) oxideMercury (I) sulfideBarium chromateAluminum hydrogen sulfateCerium (IV) nitrite

Write the formulas for theseAmmonium chlorideammonium sulfidebarium nitrate

Naming compoundsTwo typesIonic - metal and non metal or polyatomicsCovalent- we will just learn the rules for 2 non-metals

There are two methods for naming cations with multiple chargesThe Stock System and Classical SystemThe Stock system is the preferred method

Stock SystemThe stock system uses roman numerals in ( ). The ( ) indicate the numerical charge of the cation.Example:Fe2+ Name: Iron(II)There is no space between the name and the parenthesis Example:Cu1+ Name: Copper(1)

Classical SystemThe classical system uses the root word with different suffixes as the end of the wordOUS- is used to name the cation with the lower of the two ionic chargesIC- is used to name the cation with the higher of the two ionic charges

Example:Fe2+ and Fe3+Name: FerrousName: Ferric What is the problem with the classical system?

The classical system does not tell you the charge of the ion.The name only tells you which cation is either larger or smaller out of the pair

Few transition metals have only one ionic chargeThese three elements dont have roman numerals next to there nameExceptions:Ag+Cd2+Zn2+

Ionic compoundsIf the cation is monoatomic- Name the metal (cation) just write the name.If the cation is polyatomic- name itIf the anion is monoatomic- name it but change the ending to -ide If the anion is poly atomic- just name itpractice

Naming Binary Ionic CompoundsWrite the name of CuONeed the charge of CuO is -2copper must be +2Copper (II) chlorideName CoCl3 Cl is -1 and there are three of them = -3Co must be +3 Cobalt (III) chloride

Naming Binary Ionic CompoundsWrite the name of Cu2S.Since S is -2, the Cu2 must be +2, so each one is +1.copper (I) sulfideFe2O3 Each O is -2 3 x -2 = -63 Fe must = +6, so each is +2.iron (III) oxide

Ternary Ionic Compounds Will have polyatomic ions At least three elements (3 capital letters)Still just name the ionsNaNO3CaSO4CuSO3

Ternary Ionic CompoundsLiCNFe(OH)3 (NH4)2CO3NiPO4

Ionic CompoundsHave to know what ions they formoff table, polyatomic, or figure it outCaSK2SAlPO4 K2SO4FeSCoI3

Ionic CompoundsFe2(C2O4)MgOMnOKMnO4NH4NO3Hg2Cl2Cr2O3

Ionic CompoundsKClO4 NaClO3YBrO2 Cr(ClO)6

Molecular CompoundsWriting names and Formulas

Molecules & Molecular Compounds

Elements are the building materials of the substances that make up all living and nonliving thingsOnly about 100 elements but there are millions of different compounds made from their atomsThus, naming compounds is an essential skill in chemistry

In nature, only Noble Gases tend to exist as isolated atoms.They are monatomic; that is, they consist of single atomsMany elements found in nature are in the form of moleculesMolecule- is the smallest electrically neutral unit of a substance that still has the properties of the substanceMolecules are made up of two or more atoms that act as a unit

Atoms of different elements may combine chemically to form compoundsIn many compounds, the atoms combine to form molecules.Molecular Compounds- Compounds composed of moleculesMolecular Compounds tend to have relativity low melting and boiling pointsMany of these compounds thus exist as gases or liquids at room temperature.

Molecular compoundsmade of just nonmetalssmallest piece is a moleculecant be held together because of opposite charges.cant use charges to figure out how many of each atom

Naming Covalent CompoundsTwo words, with prefixesPrefixes tell you how many.mono, di, tri, tetra, penta, hexa, septa, nona, decaFirst element whole name with the appropriate prefix, except monoSecond element, -ide ending with appropriate prefixPractice

2009, Prentice-Hall, Inc.Nomenclature of Binary CompoundsThe less electronegative atom is usually listed first. A prefix is used to denote the number of atoms of each element in the compound (mono- is not used on the first element listed, however) .

2009, Prentice-Hall, Inc.Nomenclature of Binary CompoundsThe ending on the more electronegative element is changed to -ide.

CO2: carbon dioxideCCl4: carbon tetrachloride

2009, Prentice-Hall, Inc.Nomenclature of Binary CompoundsIf the prefix ends with a or o and the name of the element begins with a vowel, the two successive vowels are often elided into one.

N2O5: dinitrogen pentoxide

CO2 CO CCl4 N2O4XeF6 N4O4 P2O10 Naming Covalent Compounds

Name TheseN2ONO2 Cl2O7 CBr4 CO2 BaCl2

Covalent compoundsThe name tells you how to write the formuladuhSulfur dioxidediflourine monoxidenitrogen trichloridediphosphorus pentoxide

Write formulas for thesediphosphorus pentoxidetetraiodide nonoxidesulfur hexaflouridenitrogen trioxideCarbon tetrahydridephosphorus trifluoridealuminum chloride

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