Ch 8.2 Ionic Bond Ch 8.2 Ionic Bond PropertiesProperties

Ionic BondsIonic Bonds

• Ions – Atom or group of atoms that has Ions – Atom or group of atoms that has become electrically chargedbecome electrically charged

• Negative ion (-) – gains extra electronNegative ion (-) – gains extra electron• Positive ion (+) – loses an electronPositive ion (+) – loses an electron• Forming IONs depends upon Valence Forming IONs depends upon Valence

ElectronsElectrons– Sodium has ONE Valence Electron (wants to Sodium has ONE Valence Electron (wants to

give one away to have full electron shell)give one away to have full electron shell)– Chlorine has SEVEN Valence Electrons (wants Chlorine has SEVEN Valence Electrons (wants

to TAKE one electron to have full electron to TAKE one electron to have full electron shell)shell)

Ionic BondsIonic Bonds

• IONIC Bond is formed by the IONIC Bond is formed by the ATTRACTION between 2 ATTRACTION between 2 oppositely charged ionsoppositely charged ions

• IONIC Bonds are caused by IONIC Bonds are caused by DONATING ElectronsDONATING Electrons– Ions are electrically chargedIons are electrically charged– Ionic compounds are Ionic compounds are

electrically neutralelectrically neutral

IONIC BondsIONIC Bonds

Ionic Bonds

• The number of electrons lost by the The number of electrons lost by the Cation MUST EQUAL the number of Cation MUST EQUAL the number of electrons gained by the Anion.electrons gained by the Anion.– Calcium makes a 2+ cationCalcium makes a 2+ cation– Fluorine makes a 1- anionFluorine makes a 1- anion– Therefore it takes 2 fluorine atoms to Therefore it takes 2 fluorine atoms to

combine with one calcium atom to combine with one calcium atom to create calcium fluoridecreate calcium fluoride

– Chemical formula is CaFChemical formula is CaF22

IONIC BondsIONIC Bonds• Polyatomic Ions – an ion made of Polyatomic Ions – an ion made of

more than one atommore than one atom– COCO33 (Carbonate) (Carbonate)– SOSO44 (Sulfate) (Sulfate)

• Naming Ionic CompoundsNaming Ionic Compounds– Name of positive ion comes firstName of positive ion comes first– Name of negative ion comes second, Name of negative ion comes second,

plus plus –ide–ide– Example: NaCl = sodium chloride,Example: NaCl = sodium chloride,– Example: KI = potassium iodideExample: KI = potassium iodide

Properties of Ionic Compounds

• Crystal shapeCrystal shape– Alternate positive and negative ions in patternsAlternate positive and negative ions in patterns– Crystals are all the same shape for each Crystals are all the same shape for each

compoundcompound

• High melting pointsHigh melting points– Table Salt Melting point is 801Table Salt Melting point is 801ooCC

• Conduct electricityConduct electricity– Dissolve in waterDissolve in water– Ions become more loosely associatedIons become more loosely associated– Pass electrical charges alongPass electrical charges along

2.3 Review Questions2.3 Review Questions

1.1. How does an Ion form from an atom?How does an Ion form from an atom?– The atom gains or loses an electronThe atom gains or loses an electron

2.2. What properties may be used to What properties may be used to identify an ionic compound?identify an ionic compound?

– Crystal shape, high melting point, Crystal shape, high melting point, conducts electricityconducts electricity

3.3. Why are ions in an ionic compound Why are ions in an ionic compound attracted to each other?attracted to each other?

– They are oppositely chargedThey are oppositely charged

2.3 Review Questions2.3 Review Questions

4.4. Name these compounds: NaF, BeIName these compounds: NaF, BeI22, , KK22SOSO44, CaO, H, CaO, H22S, MgCOS, MgCO33

– Sodium fluorideSodium fluoride– Berylium IodideBerylium Iodide– Potassium SulfatePotassium Sulfate– Calcium OxideCalcium Oxide– Hydrogen SulfideHydrogen Sulfide– Magnesium CarbonateMagnesium Carbonate

2.3 Review Questions2.3 Review Questions

5.5. Solid Salt does not conduct electricity. How Solid Salt does not conduct electricity. How then does dissolving salt in water allow then does dissolving salt in water allow electricity to flow?electricity to flow?• Water breaks the ions apart, allowing the ions to Water breaks the ions apart, allowing the ions to

move freely.move freely.

6.6. The metal Scandium has 3 valence The metal Scandium has 3 valence electrons. What is the formula for the ionic electrons. What is the formula for the ionic compound formed from Scandium and compound formed from Scandium and Iodine?Iodine?– ScIScI33

– Scandium has 3 valence electrons to donate, but Scandium has 3 valence electrons to donate, but each Iodine can only take one. Therefore, it each Iodine can only take one. Therefore, it takes 3 iodines to bond with one Scandium.takes 3 iodines to bond with one Scandium.

Ionic Compounds Lab #1Substances Tested:Substances Tested:

• benzoic acid, (C6H5COOH)benzoic acid, (C6H5COOH)• magnesium chloride, (MgCl2)magnesium chloride, (MgCl2)• petrolatum (vaseline)petrolatum (vaseline)• potassium iodide (KI) replaced with potassium BROMIDE potassium iodide (KI) replaced with potassium BROMIDE

(KBr)(KBr)• sodium sulfate (Na2SO4)sodium sulfate (Na2SO4)• sucrose (C12H22O11)sucrose (C12H22O11)• sodium bicarbonate (NaHCO3)sodium bicarbonate (NaHCO3)• Unknown #1Unknown #1• Unknown #2Unknown #2

What do you observe about the unknown? What do you observe about the unknown? • Is it ionic or not? Is it ionic or not? • What do you think it might be good for? What do you think it might be good for? • What do you think it is? What do you think it is? • How could you test it further to find out?How could you test it further to find out?