Topic: Metallic Bonding

Do Now:Name as many properties of ionic compounds

you can without looking (then look to make sure you got them all

METALS

Bonds and Properties

Alloys

Pure Elements

REVIEW: Some Properties of Metals

(lowest: Fr)Low ELECTRONEGATIVITY

(lowest: Fr)Low IONIZATION ENERGY

Lose e- to form (+) ions

(except Hg)Solid at at STP

Good CONDUCTIVITY :

HEAT AND ELECTRICITY

Malleable & DuctileDEFORMABILITY

LUSTER/Shiny

Many metals have high luster

Hmmm….

How much is thisshiny Gold worth !?

400 ounces (27.5lbs)$1738.35 / ounce$695,340.00 per bar

12 ars =$8,344,080.00

Many Metals have high melting points

Metallic vs Ionic Bonding

• Both bond types due to: electrostatic attraction

• Metallic bonding: different from ionic bonding Ionic bond: transfer electrons from one

atom to another Metal bonds: electrons ROAM FREELY

from one metal atom to next sea of mobile electrons

accounts for properties of metals

Metallic bonding Metals: form organized lattice structures

similar to ionic cmpdsadjacent atoms in metal lattice are all same close proximity

of atoms allows

outer energy levels

to overlap

So…

Na 1s1 Na 1s1

electrons in outer valence shell can move freely through these overlapping energy levels = “sea of mobile electrons”

Metal bonding Freely moving electrons:

called “delocalized” electrons allows (+) metal cation to form

Delocalized electrons move freely throughout metal from one cation to nextcreates what’s called “the sea of mobile

electrons”

This sea of electrons:• binds each metal cation to

each neighbor cation • this creates the metal

bond

Metal Propertiessea of mobile electrons gives metals

some of their unique properties

since electrons move freely from place to place they:

• conduct electricity (a flow of electrons)

● conduct heat● are malleable and ductile● have luster

Electrical Conductivity

-

Free flow of electrons through the metal

+

e-e-

Flow of electrons

e- flow from metal through metal wire towards (+) charge; then flow from (-) terminal back into metal

Malleability Metals & non-metals behave very differently when hit with a force such as hammer

Metals DEFORM:Non-metals SHATTER

Metals have free flowing electrons & nonmetals do not!

If force applied to metal: •some metal atoms shift away from force & free

electrons simply bond the newly overlapping metal ions together•metal is deformed but shift doesn't change metal atoms

If force applied to Ionic compound: • like charges align (+) & (+) (-) & (-) which results in shattering due to force of repulsion

Metals DEFORM:Ionic Cmpds SHATTER

Deformation of MetalsDeformation of Metals

As # of electrons that can be delocalized ↑ so does: Hardness and StrengthEXAMPLES:• Na has one valence electron that can be delocalized

- is relatively soft ( can be cut with a butter knife)• Mg has two electrons that can be delocalized so:

- can still be cut but is much harder than Na• Transition metals have varied # of e-'s that can be

delocalized- Chromium is very hard and has high strength

Alloysmixture of elements that have metallic

propertiesmixture can be adjusted to get desired

propertiescan be substitutional

(elements of the same size)

or interstitial (elements that are different sizes)

Common alloys Brass: Cu & Zn Bronze: Cu, Sn & Al Pewter: Sn, Pb & Cu Solder: Pb & Sn Rose gold: Cu & Al

White gold: Au & Ni, Pd or Pt

Sterling silver: Ag & Cu

Steel: C & Fe Stainless steel: Cr & Ni