Properties of bondingProperties of bonding

Mrs. KayMrs. Kay

Properties of Ionic bondingProperties of Ionic bonding

Determined by their crystalline structures Determined by their crystalline structures (how the crystals form)(how the crystals form)

Solid at room temperature (no movement)Solid at room temperature (no movement) High melting points = strong bondsHigh melting points = strong bonds Very hard and brittleVery hard and brittle

Molten compounds Molten compounds conduct electricityconduct electricity

Solid structure does Solid structure does not conduct electricity not conduct electricity because of rigidity because of rigidity and no ionic and no ionic movement for movement for electricity to pass electricity to pass through.through.

StrengthStrength

Depends on the radii and charges on the Depends on the radii and charges on the ionsions

Increasing metallic charge= stronger Increasing metallic charge= stronger bonds = highest melting pointsbonds = highest melting points

Which would produce stronger bonds NaWhich would produce stronger bonds Na++, , CaCa+2+2, or Al, or Al+3+3??

NaNa+ + < Ca< Ca+2 +2 < Al< Al+3+3

SolubilitySolubility

Most are soluble (can Most are soluble (can dissolve into ions) in dissolve into ions) in polar solvents (ex: polar solvents (ex: water, ammonia)water, ammonia)

These solutions do These solutions do conduct electricity conduct electricity because of mobile because of mobile ions (electrolytes)ions (electrolytes)

HydrationHydration

The process The process which polar which polar solvent molecules solvent molecules interact with ions interact with ions in the crystal in the crystal lattice and cause lattice and cause the ionic crystal to the ionic crystal to dissolve, releasing dissolve, releasing ions into solutionions into solution

Water surrounds Water surrounds the ion (ion-dipole the ion (ion-dipole interactions)interactions)

Properties of simple covalent Properties of simple covalent moleculesmolecules

Covalent molecules exist as s, l, or gCovalent molecules exist as s, l, or g Usually softUsually soft Evaporate easier than ionicEvaporate easier than ionic Low melting and boiling pointsLow melting and boiling points

Do not conduct Do not conduct electricity in liquid or electricity in liquid or solid statesolid state

Not soluble in polar Not soluble in polar solvents, but may be solvents, but may be soluble in nonpolar soluble in nonpolar solvents (CClsolvents (CCl44 or or

gasoline)gasoline)

Napthalene (smells like Napthalene (smells like moth balls)moth balls)

Note:Note:

Molecules: any electrically neutral group Molecules: any electrically neutral group of atoms that are bonded tightly together of atoms that are bonded tightly together to be considered one particle.to be considered one particle.

Ex: ClEx: Cl22, NH, NH33, H, H22OO

Ionic compounds are not molecules!!!Ionic compounds are not molecules!!! NaCl is not one molecule but a crystal NaCl is not one molecule but a crystal

lattice structure with attractive forces lattice structure with attractive forces holding them together.holding them together.

Metallic BondingWhat is a Metallic Bond?

- A metallic bond occurs in metals. A metal consists of positive ions surrounded by a “sea” of mobile electrons.

Name 4 Characteristics of a Metallic Bond.

1. Good conductors of heat and electricity

2. Great strength

3. Malleable and Ductile

4. Luster

This shows what a metallic bond might look like.

Metallic bondMetallic bond

Occurs between Occurs between atoms with low atoms with low electronegativitieselectronegativities

Metal atoms pack Metal atoms pack close together in 3-D, close together in 3-D, like oranges in a box.like oranges in a box.

Close-packed lattice Close-packed lattice formationformation

Many metals have an Many metals have an unfilled outer orbitalunfilled outer orbital

In an effort to be energy In an effort to be energy stable, their outer stable, their outer electrons become electrons become delocalised amongst all delocalised amongst all atomsatoms

No electron belongs to No electron belongs to one atomone atom

They move around They move around throughout the piece of throughout the piece of metal.metal.

Metallic bonds are not Metallic bonds are not ions, but nuclei with ions, but nuclei with moving electronsmoving electrons

Physical PropertiesPhysical Properties

ConductivityConductivity Delocalised electrons are Delocalised electrons are

free to move so when a free to move so when a potential difference is potential difference is applied they can carry the applied they can carry the current alongcurrent along

Mobile electrons also Mobile electrons also mean they can transfer mean they can transfer heat wellheat well

Their interaction with light Their interaction with light makes them shiny (lustre)makes them shiny (lustre)

MalleabilityMalleability

The electrons are attracted The electrons are attracted the nuclei and are moving the nuclei and are moving around constantly.around constantly.

The layers of the metal The layers of the metal atoms can easily slide past atoms can easily slide past each other without the need each other without the need to break the bonds in the to break the bonds in the metalmetal

Gold is extremely malleable Gold is extremely malleable that 1 gram can be that 1 gram can be hammered into a sheet that hammered into a sheet that is only 230 atoms thick (70 is only 230 atoms thick (70 nm)nm)

Melting pointsMelting points

Related to the energy Related to the energy required to deform (MP) required to deform (MP) or break (BP) the metallic or break (BP) the metallic bondbond

BP requires the cations BP requires the cations and its electrons to break and its electrons to break away from the others so away from the others so BP are very high.BP are very high.

The greater the amount The greater the amount of valence electrons, the of valence electrons, the stronger the metallic stronger the metallic bond.bond.

Gallium can melt in your Gallium can melt in your hand at 29.8 hand at 29.8 ooC, but it C, but it boils at 2400 boils at 2400 ooC!C!

AlloysAlloys Alloying one metal with other metal(s) or non Alloying one metal with other metal(s) or non

metal(s) often enhances its properties metal(s) often enhances its properties Steel is stronger than pure iron because the carbon Steel is stronger than pure iron because the carbon

prevents the delocalised electrons to move so readily.prevents the delocalised electrons to move so readily. If too much carbon is added then the metal is brittle.If too much carbon is added then the metal is brittle.

They are generally less malleable and ductileThey are generally less malleable and ductile Some alloys are made by melting and mixing Some alloys are made by melting and mixing

two or more metals two or more metals Bronze = copper and zincBronze = copper and zinc Steel = iron and carbon (usually)Steel = iron and carbon (usually)

Network Covalent Molecules:Network Covalent Molecules:Allotropes of carbonAllotropes of carbon

elements can exist in two or more different elements can exist in two or more different forms because the element's atoms are forms because the element's atoms are bonded together in a different manner bonded together in a different manner

Carbon has 3 allotrophesCarbon has 3 allotrophes DiamondDiamond GraphiteGraphite Fullerenes (CFullerenes (C6060))

• NanotubesNanotubes• Buckminster FullereneBuckminster Fullerene

DiamondsDiamonds

carbon atoms are bonded carbon atoms are bonded together in a tetrahedral lattice together in a tetrahedral lattice arrangement (3D framework)arrangement (3D framework)

Giant covalent structureGiant covalent structure Very strong, so they require a Very strong, so they require a

lot of energy to break themlot of energy to break them M.P is 3820 KM.P is 3820 K Does NOT conduct electricityDoes NOT conduct electricity 4x harder than any other 4x harder than any other

natural mineralnatural mineral

GraphiteGraphite

has a sheet like structure has a sheet like structure where the atoms all lie in a where the atoms all lie in a plane and are only weakly plane and are only weakly bonded to the sheets above bonded to the sheets above and below. (2D framework)and below. (2D framework)

Much softer, conducts Much softer, conducts electricity. (delocalised electricity. (delocalised electron)electron)

The C-C bonds are still quite The C-C bonds are still quite strong.strong.

Each carbon bonded to 3 other Each carbon bonded to 3 other carbon.carbon.

Fullerene CFullerene C6060

consists of 60 carbon atoms consists of 60 carbon atoms bonded in the nearly spherical bonded in the nearly spherical configuration configuration

CC6060 is highly electronegative, is highly electronegative, meaning that it readily forms meaning that it readily forms compounds compounds

Low solubility, low conductivity Low solubility, low conductivity (greater than diamond, but much (greater than diamond, but much lower than graphite)lower than graphite)

Buckminster Fullerene (photo) Buckminster Fullerene (photo) made up of hexagon and made up of hexagon and pentagon carbon formationspentagon carbon formations

Also includes nanotubes Also includes nanotubes (cylindrical) Made up of (cylindrical) Made up of hexagons of carbonhexagons of carbon