Transcript Slide 1

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
Alloys
Pure Elements
Bonds and
Properties
REVIEW:
Some Properties of Metals
LUSTER/Shiny
DEFORMABILITY
Malleable & Ductile
Good CONDUCTIVITY :
HEAT AND ELECTRICITY
Solid at at STP
(except Hg)
Lose e- to form (+) ions
Low IONIZATION ENERGY
(lowest: Fr)
Low ELECTRONEGATIVITY
(lowest: Fr)
Many metals have high luster
Hmmm….
How much is this
shiny 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 cmpds
 adjacent
atoms in metal lattice are all same
 close proximity
of atoms allows
Na 1s1
Na 1s1
outer energy levels
to overlap
So…
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 next
 creates 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 Properties
sea 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
+-
e- 
Flow of electrons
 e-
Free flow of electrons through the metal
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!
Metals DEFORM:
Ionic Cmpds SHATTER
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
Deformation of Metals
Deformation of Metals
As # of electrons that can be delocalized ↑ so does:
Hardness and Strength
EXAMPLES:
• 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
Alloys
 mixture
of elements that have metallic
properties
 mixture can be adjusted to get desired
properties
 can be substitutional
(elements of the same size)
or interstitial
(elements that are different sizes)
 Brass:
Common alloys
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