Chapter 7Chapter 7

Ionic and Metallic BondingIonic and Metallic Bonding

Sodium chloride

Hydrogen

peroxide

Magnesium sulphate

Nitrogen dioxide

Hydrochloric acid

Calciu

m fl

uorid

e

Carbon monoxide

MOLECULAR VS. IONIC MOLECULAR VS. IONIC COMPOUNDSCOMPOUNDS

MOLECULAR COMPOUNDS:MOLECULAR COMPOUNDS:1. Low melting & boiling points1. Low melting & boiling points2. Solids, Liquids, and Gases at room 2. Solids, Liquids, and Gases at room temp.temp.3. Sharing of valence electrons3. Sharing of valence electrons4. Two or more 4. Two or more Nonmetallic elementsNonmetallic elements5.5. Contain covalent bondsContain covalent bonds

EX:EX:HH22OO COCO22

MOLECULAR VS. IONIC MOLECULAR VS. IONIC COMPOUNDSCOMPOUNDS

IONIC COMPOUNDS:IONIC COMPOUNDS:1. High melting & boiling points1. High melting & boiling points2. Composed of ions (cation and anion)2. Composed of ions (cation and anion)3. Electrically neutral3. Electrically neutral4. Crystalline solids at room 4. Crystalline solids at room temperaturetemperature

-coordination #, 3D patterns-coordination #, 3D patterns5. Composed of a 5. Composed of a MetalMetal and and NonmetalNonmetal6. Contains Electrostatic Bonds6. Contains Electrostatic Bonds

EX:EX:NaClNaCl MgClMgCl22

                                                                                          Ionic Bonds: Ionic Bonds: One big greedy thief dog!One big greedy thief dog!

Ionic bonding can be best imagined as one big greedy Ionic bonding can be best imagined as one big greedy dog steeling the other dog's bone.  If the bone dog steeling the other dog's bone.  If the bone represents the electron that is up for grabs, then when represents the electron that is up for grabs, then when the big dog gains an electron he becomes negatively the big dog gains an electron he becomes negatively charged and the little dog who lost the electron becomes charged and the little dog who lost the electron becomes positively charged.  The two ions (that's where the name positively charged.  The two ions (that's where the name ionic comes from) are attracted very strongly to each ionic comes from) are attracted very strongly to each other as a result of the opposite charges.other as a result of the opposite charges.

CHEMICAL FORMULA:CHEMICAL FORMULA:

Shows the kinds and number Shows the kinds and number

of atoms in the of atoms in the

smallestsmallest representative unit representative unit

of the substance.of the substance.

IONIC FORMULA:IONIC FORMULA:1. Ionic compounds exist as formula units. 1. Ionic compounds exist as formula units.

2. Shows the 2. Shows the lowestlowest whole-number ratio whole-number ratio of ions present in an ionic compoundof ions present in an ionic compound ((formula unitformula unit).).

EX:EX:NaCl (sodium chloride) NaCl (sodium chloride) Na+1 Cl-1Na+1 Cl-1 1:1 ratio1:1 ratio

MgClMgCl22 (magnesium chloride) (magnesium chloride) Mg+2 Cl-1Mg+2 Cl-11:2 ratio1:2 ratio

Ionic CompoundsIonic Compounds

How to Write an Ionic How to Write an Ionic Formula:Formula:

1. Write down symbols1. Write down symbols

2. Determine Ionic Charges2. Determine Ionic Charges

3. Charges must cancel each other out 3. Charges must cancel each other out

(equal zero)(equal zero)

– if not, use criss-cross method to if not, use criss-cross method to form subscripts to cancel out chargesform subscripts to cancel out charges

EXAMPLES:EXAMPLES:Potassium BromidePotassium Bromide KK+1+1 Br Br-1 -1 charges cancel charges cancel KBrKBr

Magnesium OxideMagnesium Oxide MgMg+2 +2 O O-2-2 charges cancelcharges cancel MgOMgO

Aluminum NitrideAluminum Nitride AlAl+3+3 N N-3-3 charges cancel charges cancel AlNAlN

Magnesium ChlorideMagnesium Chloride MgMg+2+2 Cl Cl-1-1 charges don’t cancel, charges don’t cancel, criss-cross criss-cross MgClMgCl22Sodium SulfideSodium Sulfide NaNa+1+1 S S-2-2 charges don’t cancel, charges don’t cancel, criss-crosscriss-cross NaNa22SSAluminum Oxide Aluminum Oxide AlAl+3+3 O O-2-2 charges don’t cancel, charges don’t cancel, criss-crosscriss-cross AlAl22OO33

Naming an Ionic Formula:Naming an Ionic Formula:1. Write the name for the metal and 1. Write the name for the metal and

nonmetalnonmetal

2. Check to see if the metal has more than 2. Check to see if the metal has more than

one charge (Cu, Fe, transition metals)one charge (Cu, Fe, transition metals)

3. If metal has more than one charge, you 3. If metal has more than one charge, you

must do a “reverse” criss-cross to must do a “reverse” criss-cross to

determine formuladetermine formula– A Roman Numeral goes between the two A Roman Numeral goes between the two

namesnames

4. Change the nonmetal ending to 4. Change the nonmetal ending to IDEIDE

EXAMPLES:EXAMPLES:

KBrKBr potassium bromide potassium bromide

NaNa22O O sodium oxidesodium oxide

MgS MgS magnesium sulfidemagnesium sulfide

Cu BrCu Br22 copper II bromide copper II bromide

AsAs22 O O55 arsenic V oxide arsenic V oxide

FeFe22 O O3 3 iron III oxideiron III oxide

Metallic BondsMetallic Bonds

Consist of the attraction of the free-Consist of the attraction of the free-floating valence electrons for the floating valence electrons for the

positively charged metal ions.positively charged metal ions.

Lets Remember:Lets Remember: Good conductors of electricity & heatGood conductors of electricity & heat Ductile & malleableDuctile & malleable Metals have 1,2, or 3 valence electronsMetals have 1,2, or 3 valence electrons Low ionization energies :Low ionization energies :

(easy to remove valence electrons)(easy to remove valence electrons)

Therefore:Therefore:

1. Valence electrons don’t belong to any 1. Valence electrons don’t belong to any

individual atom.individual atom.

2. Valence electrons exist as a sea around 2. Valence electrons exist as a sea around closely closely

packed metal cations.packed metal cations.Cation

Sea of valence electrons

3. Metal cations are insulated from one 3. Metal cations are insulated from one anotheranother

by a sea of drifting valence electrons by a sea of drifting valence electrons

(ballbearings in oil)(ballbearings in oil)

4. Metals are simplest crystalline solids4. Metals are simplest crystalline solids

5. Orderly compact pattern5. Orderly compact pattern

Cation

Sea of valence electrons

Metallic Bonds:  Mellow Metallic Bonds:  Mellow dogs with plenty of bones dogs with plenty of bones to go around to go around

These bonds are best imagined as a room full of These bonds are best imagined as a room full of puppies who have plenty of bones to go around and are puppies who have plenty of bones to go around and are not possessive of any one particular bone.  This allows not possessive of any one particular bone.  This allows the electrons to move through the substance with little the electrons to move through the substance with little restriction.  The model is often described as the "kernels restriction.  The model is often described as the "kernels of atoms in a sea of electrons."of atoms in a sea of electrons."

Laws of ProportionsLaws of ProportionsI. I. Law of Definite Proportions:Law of Definite Proportions:

A chemical compound always contains A chemical compound always contains the same elements in exactly the same the same elements in exactly the same proportions by mass.proportions by mass.

Any two samples of a given compound Any two samples of a given compound are made of the same elements in are made of the same elements in exactly the same proportions by mass.exactly the same proportions by mass.

Law of Definite Law of Definite Proportions:Proportions:

EX:EX: HH22OO

2g 16g 1:8 mass ratio 2g 16g 1:8 mass ratio

always for any compound of wateralways for any compound of water

CO and COCO and CO22

Laws of ProportionsLaws of Proportions

II. II. Law of Multiple Proportions: Law of Multiple Proportions:

(comparing 2 different cmpds)(comparing 2 different cmpds)

When two elements combine to form two When two elements combine to form two or more compounds, the mass of one or more compounds, the mass of one element that combines with a given element that combines with a given mass of the other is in the ration of mass of the other is in the ration of small small whole numberswhole numbers..

Law of Multiple Law of Multiple Proportions:Proportions:

EX: EX: Carbon reacts with oxygen to form Carbon reacts with oxygen to form

2 cmpds. 2 cmpds.

Cmpd. A contains 2.41 g of C for each Cmpd. A contains 2.41 g of C for each

3.22 g of O. Cmpd. B contains 6.71 g 3.22 g of O. Cmpd. B contains 6.71 g of C of C for each 17.9 g of O. What is the for each 17.9 g of O. What is the lowest lowest whole number ratio of C that whole number ratio of C that combines combines with a given mass of with a given mass of oxygen? oxygen?

Law of Multiple Law of Multiple Proportions:Proportions:

EX:EX: Two compounds that contain H and Two compounds that contain H and O O are hydrogen peroxide and water.are hydrogen peroxide and water.

1.1. Demonstrate the Law of Definite Demonstrate the Law of Definite Proportions for these two compounds.Proportions for these two compounds.

2.2. Find the mass ratio of oxygen in Find the mass ratio of oxygen in these these 2 cmpds.2 cmpds.