Ions & Ionic Compounds

Ions & Ionic CompoundsSection 1: Simple IonsObjectivesRelate electron configuration of an atom to its chemical reactivityDetermine an atoms number of valence electrons, and use the octet rule to predict what stable ions the atom is likely to form Explain why properties of ions differ from those of their parent atomsChemical ReactivityNoble gases are the least reactive elements posses full outer energy levels ns2np6In most chemical reactions, atoms in the main-group tend to match the e- configurations of noble gases. An atom whose outer s and p orbitals do not match the e- configuration of a noble gas will react to lose or gain e- so the outer orbitals will be full. Octet Rule: a concept of chemical bonding theory that is based on the assumption that atoms tend to try and achieve full valence shells of eight electrons.

Valence ElectronsThe periodic table reveals an atoms number of valence electrons.

1. Look for the previous noble gas.3. Look at which period it is in. 2. Look at the unit number of the groupValence ElectronsIon: an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive chargeAn ion with a positive charge is called a cation (memory tip: the t is like a + sign!)K K+ + e- [K] = 1s22s22p63s23p64s1[K+] = 1s22s22p63s23p6An ion with a negative charge is called an anion. Cl + e- Cl-[Cl] = 1s22s22p63s23s5[Cl-] = 1s22s22p63s23s6

Noble-Gas ConfigurationsMany stable ions have noble-gas configurations.

Group 13Group 15Group 16Group 17Group 18Non Noble-gas ConfigurationsNot all elements form noble-gas configurations.Transition metals often form ions without complete octets.Some elements (mostly transition metals) can form several stable ions with different charges.

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Atoms & IonsIons and their parents atoms have different propertiesE.g. Sodium and ChlorineSodium is in group 1 and is highly reactive. Chlorine is in group 17 and is also highly reactive.Reacted together, however, they form a stable, inert compound sodium chloride.Atoms of metals always form cations. Na+Because it takes less energy to lose e- to achieve a stable configurationAtoms of nonmetals always form anions. Cl-Because it takes less energy to gain e- to achieve a stable configuration

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Quick QuestionsWhich elements are the least reactive on the periodic table?How many valence electrons are found in atoms located in group 1, 2, 16 and 17 on the periodic table?What is an anion? A cation?Which class of elements tend to form stable ions that do not have noble-gas configurations?Metals form [positive/negative] ions.Elements from periods 1, 2 and 3 form ions that have the same electron configurations as which group of elements from the periodic table?Ionic bonding and saltsChapter 5: Section 2ObjectivesDescribe the process of forming an ionic bondExplain how the properties of ionic compounds depend on the nature of ionic bondsDescribe the structure of salt crystalshttps://www.youtube.com/watch?v=QXT4OVM4vXI Ionic BondingAn ionic bond is a chemical bond formed by attractions between two ions(metal & a nonmetal) with opposite charges.https://www.youtube.com/watch?v=zpaHPXVR8WU

Ionic BondingNaCl is a salt which is formed through ionic bonding. Na+ cation forms when 1 e- is given up. This 1 e- is acquired by a chlorine atom to form Cl-.

Ionic BondingThere is a force of attraction between the positive and negative ions. NaCl are attracted to each other and form a compound with a 1:1 ratio. Many different ions are pulled together into a tightly packed structure which produces a crystal shape.

Transferring Electrons Involves EnergyMoving a negatively charged electron away from an atom that will become a positively charged ion requires an input of energy. (ionization energy)

Na + energy Na+ + e-

Generally, energy is required to add an electron to a neutral atom. However, some elements easily accept electrons and instead release energy

Cl + e- Cl- + energyThe Energy of Salt FormationThe process of form a salt can be broken down into 5 steps. 1Energy added to convert solid metal gasENDOTHERMIC2Energy added to remove electron from each metal atom to form a cation3Energy added to break apart non-metal atoms4Energy released as electron is added to non-metal atom to form an anionEXOTHERMIC5Large amount of energy released as cation and anion come together to form salt crystal

PropertyIonic Solids?Why is this the case?Melting pointVery highDifficult to break the strong electrostatic bonds requires a large amount of heat energy to before the particles are sufficiently far apart to allow them to change stateStrength of BondsVery strongBecause of the closely packed lattice structure and the strong ionic bonds between charged ions requires a large amount of energy to break bondsBrittlenessBrittleForces of repulsion are developed between the ions when stress is applied the electrostatic propulsion can be enough to split the compound apartConductivityConducts when dissolved in a solvent or in a molten stateDissolved: the solvent frees the ions from their fixed positions Molten: ions are free to move in the liquid stateProperties of Ionic CompoundsIonic compounds do not consist of individual moleculesInstead, they consist of many ions, all bonded together to form a crystal structure. The formula represents the ratio of cation to anion only (e.g. NaCl)

Properties of Ionic CompoundsIonic Bonds are Strong!Repulsive forces exist between ions with the same charge (between Na+ ions and Na+ ions)Attractive forces, however, are far stronger every positive ion is surrounded by many negative ions and vice versaThis results in a very strong structure far stronger than individual molecules of ionsIonic Compounds have high melting and boiling pointsA lot of energy is needed to break the strong bonds between ions and change a solid liquid or a liquid gas

Properties of Ionic CompoundsIonic Compounds conduct electricity when dissolved or as a liquidIn order to conduct electricity, substance must a) contain charged particles b) these particles must be free to moveAs a solid, particles are locked in place and are unable to moveAs a liquid, particles are able to slide past one another move freelyWhen dissolved, ions break apart and are free in solution.

Properties of Ionic CompoundsIonic compounds are hard and brittleHard requires a large amount of force to break the crystal apartBrittleness if a substance is brittle is does not deform when a force is applied to it. Brittle substances shatter when the force applied exceeds the strength of the bonds holding them together

PropertyIonic Solids?Why is this the case?Melting pointVery highDifficult to break the strong electrostatic bonds requires a large amount of heat energy to before the particles are sufficiently far apart to allow them to change stateStrength of BondsVery strongBecause of the closely packed lattice structure and the strong ionic bonds between charged ions requires a large amount of energy to break bondsBrittlenessBrittleForces of repulsion are developed between the ions when stress is applied the electrostatic propulsion can be enough to split the compound apartConductivityConducts when dissolved in a solvent or in a molten stateDissolved: the solvent frees the ions from their fixed positions Molten: ions are free to move in the liquid stateSalt CrystalsSalts vary in the types of ions from which they are made.Salts vary in the ratio of ions that make up the crystal latticeNaCl is a 1:1 ratio of Na to ClMgCl2 is a 1:2 ratio of Mg to ClThe smallest repeating unit in a crystal lattice is called a unit cellThe structure of crystals can be determined using x-ray crystallography

Names and formulas of ionic compoundsChapter 5: Section 336Naming Ionic Compounds with Two Elements To name a compound that contains two elements,

identify the cation and anion.mame the cation first followed by the name of the anion.

37Charges of Representative Elements

Copyright 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings38Names of Some Common Ions

Copyright 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings39Complete the names of the following ions. Ba2+Al3+K+ _________ __________ _________

N3 O2 F _________ __________ _________

P3 S2 Cl _________ __________ _________ Learning Check40Ba2+Al3+K+barium aluminum potassium N3 O2 F nitride oxide fluoride

P3 S2 Cl phosphide sulfide chlorideSolution41 Formula IonsName cation anionNaClNa+ Cl-sodium chlorideK2SK+ S2-potassium sulfideMgOMg2+ O2-magnesium oxideCaI2Ca2+ I-calcium iodideAl2O3Al3+ O2-aluminum oxide

Examples of Ionic Compounds with Two Elements42Write the names of the following compounds.

1) CaO___________2) KBr___________3) Al2O3___________ 4) MgCl2___________

Learning Check43Write the names of the following compounds:

1)CaOcalcium oxide2)KBrpotassium bromide3)Al2O3aluminum oxide4)MgCl2magnesium chloride

Solution44Learning CheckWrite the formulas and names for compounds of the following ions: Br S2 N3

Na+

Al3+ 45Solution Br S2 N3

Na+

Al3+ NaBrsodium bromideNa2Ssodium sulfideNa3Nsodium nitrideAlBr3aluminum bromideAl2S3aluminum sulfideAlNaluminum nitride

46

Transition Metals form Positive Ions

Most transition metals and Group 4(14) metals form 2 or more positive ions.

Zn2+, Ag+, and Cd2+ form only one ion.

47Metals that form more than One CationThe name of metals with two or more positive ions(cations) use a Roman numeral to identify ionic charge.

Copyright 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

Lead Pb2+ lead(II) Pb4+ lead(IV)

Writing Formula for Simple Ionic CompoundsIonic compounds must have no overall charge. Write the symbol and charges for the cation and anion.Write the symbols for the ions side by side, beginning with the cation.swap and drop the charges.Find the lowest common multiple, if necessary. 49Learning CheckWhat is the correct formula for each of the following?A. Copper(I) nitride 1) CuN2) CuN3 3) Cu3N

B. Lead(IV) oxide 1) PbO22) PbO 3) Pb2O4

50SolutionThe correct formula isA. Copper (I) nitride 3) Cu3NNeed 3Cu+ and N3-

B. Lead (IV) oxide 1) PbO2Need Pb4+ and 2O2-51Naming Ionic Compounds with Variable Charge Metals

Copyright 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings52Naming Variable Charge MetalsTransition metals with two different ions use a Roman numeral after the name of the metal to indicate ionic charge.

53Naming FeCl2To name FeCl21. Determine the charge of the cation using the charge of the anion (Cl-).Fe ion + 2 Cl- = Fe ion + 2- = 0Fe ion = 2+2. Name the cation by the element name and add a Roman numeral in parenthesis to show its charge.Fe2+ = iron(II)3. Write the anion with an ide ending. FeCl2 = iron(II) chloride

54Naming Cr2O3To name Cr2O31. Determine the charge of cation from the anion (O2-).2 Cr ions + 3 O2- = 02 Cr ions + 3(2-) = 0 2 Cr ions - 6 = 02 Cr ions = +6 Cr ion = 3+ = Cr3+2. Name the cation by the element name and add a Roman numeral in parenthesis to show its charge.Cr3+ = chromium(III)3. Write the anion with an ide ending. chromium(III) oxide = Cr2O3

55Learning CheckSelect the correct name for each.A. Fe2S3 1) iron sulfide 2) iron(II) sulfide 3) iron(III) sulfide

B. CuO 1) copper oxide 2) copper(I) oxide 3) copper(II) oxide 56SolutionSelect the correct name for each.A. Fe2S3 3) iron (III) sulfide Fe3+ S2-

B. CuO 3) copper (II) oxide Cu2+ O2-57A polyatomic ion Is a group of atoms. Has an overall ionic charge.

Some examples of polyatomic ions areNH4+ ammoniumOH hydroxideNO3 nitrateNO2 nitriteCO32carbonatePO43 phosphateHCO3 hydrogen carbonateSO42- sulfate(bicarbonate)

Polyatomic Ions58Some Compounds with Polyatomic Ions

Copyright 2008 by Pearson Education, Inc.Publishing as Benjamin Cummings59The names of common polyatomic anions Some end in ate. NO3 nitratePO43 phosphateSome end in ite. NO2 nitritePO33 phosphiteSome will have hydrogen in name (or bi).HCO3 hydrogen carbonate (bicarbonate)HSO3 hydrogen sulfite (bisulfite)

More Names of Polyatomic Ions60Names and Formulas of Common Polyatomic Ions

Copyright 2008 by Pearson Education, Inc.Publishing as Benjamin Cummings61Names and Formulas of Common Polyatomic Ions

Copyright 2008 by Pearson Education, Inc.Publishing as Benjamin Cummings62Similar polyatomic ions will have similar names.

ClO4 perchlorateone oxygen moreClO3 chloratemost common formClO2 chloriteone oxygen lessClO hypochlorite two oxygens less

Prefixes for Names of Polyatomic Ions of HalogensParenthesesIf you need two or more Polyatomic ions, YOU MUST USE Parentheses with the subscript.Write the formula for Cu+2 and NO3-1You need 1 Cu+2 and 2 NO3-1

You would write it like this: Cu(NO3)2

The 2 tells us we need 2 of the NO3-1 ions.6364The positive ion is named first followed by the name of the polyatomic ion.NaNO3sodium nitrateK2SO4potassium sulfateFe(HCO3)3iron(III) bicarbonate or iron(III) hydrogen carbonate(NH4)3PO3ammonium phosphite

Naming Compounds with Polyatomic Ions65Some Compounds with Polyatomic Ions

Table 5.7 Copyright 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings66Select the correct formula for each:A. aluminum nitrate 1) AlNO3 2) Al(NO)3 3) Al(NO3)3B. copper(II) nitrate 1) CuNO32) Cu(NO3)23) Cu2(NO3)C. iron (III) hydroxide 1) FeOH2) Fe3OH3) Fe(OH)3D. tin(IV) hydroxide 1) Sn(OH)4 2) Sn(OH)2 3) Sn4(OH)

Learning Check67Select the correct formula for each:A. aluminum nitrate 3) Al(NO3)3B. copper(II) nitrate 2) Cu(NO3)2C. iron(III) hydroxide 3) Fe(OH)3D. tin(IV) hydroxide 1) Sn(OH)4

Solution68Match each formula with the correct name:A. MgS1) magnesium sulfite MgSO32) magnesium sulfate MgSO43) magnesium sulfide

B. Ca(ClO3)21) calcium chlorate Ca(ClO)22) calcium chlorite Ca(ClO2)2 3) calcium hypochloriteLearning Check69Match each formula with the correct name:A. MgS3) magnesium sulfide MgSO31) magnesium sulfite MgSO42) magnesium sulfate

B. Ca(ClO3)21) calcium chlorate Ca(ClO)23) calcium hypochlorite Ca(ClO2)2 2) calcium chloriteSolution70Learning CheckName each of the following compounds:

A.Mg(NO3)2B.Cu(ClO3)2C.PbO2D.Fe2(SO4)3E.Ba3(PO3)2

71SolutionName each of the following compounds:

A.Mg(NO3)2magnesium nitrateB.Cu(ClO3)2copper(II) chlorateC.PbO2lead (IV) oxideD.Fe2(SO4)3iron(III) sulfateE.Ba3(PO3)2barium phosphite

72Writing Formulas with Polyatomic IonsThe formula of an ionic compound Containing a polyatomic ion must have a charge balance that equals zero(0).Na+ and NO3 NaNO3

With two or more polyatomic ions encloses the polyatomic ions in parentheses.Mg2+ and 2NO3 Mg(NO3)2 subscript 2 for charge balance73Learning CheckWrite the correct formula for each:A.potassium bromateB.calcium carbonateC.sodium phosphateD.iron(III) oxideE.iron (II) nitrite

74SolutionWrite the correct formula for each:A.potassium bromateKBrO3B.calcium carbonateCaCO3C.sodium phosphateNa3PO4D.iron(III) oxideFe2O3E.iron (II) nitriteFe(NO2)275Naming Ionic Compounds

Copyright 2008 by Pearson Education, Inc. Publishing as Benjamin CummingsTable 5.876Flowchart for Naming

Copyright 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings77Learning CheckName the following compounds:A. Ca3(PO4)2B. FeBr3C. Al2S3D. Mn(NO2)2E. NaHCO378SolutionName the following compounds:A. Ca3(PO4)2 Ca2+ PO43 calcium phosphateB. FeBr3 Fe3+ Br iron(III) bromideC. Al2S3 Al3+ S2 aluminum sulfideD. Mn(NO2)2 Mn2+ NO2 manganese(II) nitriteE. NaHCO3 Na+ HCO3 sodium hydrogen carbonate or sodium bicarbonate79Learning CheckWrite the formulas for the following:A. calcium nitrateB. iron(II) hydroxideC. aluminum carbonateD. copper(II) bromideE. lithium phosphate80SolutionWrite the formulas for the following:A. calcium nitrateCa2+, NO3 Ca(NO3)2 B. iron(II) hydroxideFe2+, OH Fe(OH)2 C. aluminum carbonateAl3+, CO32 Al2(CO3) 3D. copper(II) hypobromite Cu2+, Br- CuBr2 E. lithium phosphateLi+, PO43 Li3PO4