1. Metallic Bonding

2. Metallic Bonding A metallic bond is the attraction+ + + + +
Delocalized e- + + + + +
AKA
Sea of e- + + + + + + + + + +
A metallic bond is the attraction
of a ________ _______for ____________electrons
Metallic cation
delocalized

3. The Electron Sea
Electron Sea Model proposes that the nuclei of the metallic cations hold onto their correct ________ of _________, but they may be any valence e- of a neighboring nucleus.
number
electrons

4. The Electron Sea
They are NOT ______ or _____; like in covalent bonds. Instead, they are floating in a sea above the _______ and can move freely from one atom to the next.
shared
lost
nuclei

6. delocalized electron =
Attractions between positive cations and the negative “sea of e-“ hold the metal atoms together in a lattice.
The valence e- of a metal that are free to move easily from one cation to another

7. Properties of metals med. high melting points high boiling points
malleable and ductile
heat conductors
electrical conductors

8. Brittleness is typical of ionic substances
Brittleness is typical of ionic substances. Imagine what happens to the crystal if a stress is applied which shifts the ion layers slightly.
Ions of the same charge are brought side-by-side and so the crystal repels itself to pieces! + + + + + + + + + + + + + + + + + + + +

9. Malleability of metals
Whereas ionic compounds shatter when hit with a mallet (hammer), metallic compounds can be flattened and shaped. Why?
The sea of electrons acts as a lubricant.
By covering the metal cations, it allows them to slide past each other without repelling. + + + + + + + + +

10. As the number of increases, increase
As the number of increases, increase. In the transition metals, mobile electrons consist of both the electrons (highest s) and the inner electrons.
delocalized electrons
hardness & strength
valence d

11. Alloy = mixture of metal + another element; not a compound
18 carat Gold Au 75% Ag/Cu 25%
Sterling silver Ag 92.5% Cu 7.5%
Coinage silver Ag 90% Cu 10%
Plumber’s solder Pb 67% Sn 33%
Pewter Sn 85% Cu 7.3% Bi 6% Sb 1.7%
Brass Cu 60% Zn 39% Sn 1%
Steel Fe 99% C 1%
Cast Iron Fe 96% C 4%
Stainless Steel Fe 80.6% Cr 18% C 0.4% Ni 1%

12. Types of alloys
When two metals with similar size ions are mixed, a alloy is formed
examples:
substitutional
Brass, pewter, 14 carat gold
Tin
Copper
Bronze

13. When one of the metals’ ions is considerably smaller than the other metal, the smaller ions fill in the small spaces (___________) between the larger ones. This is an __________ _____
example:
interstices
Interstitial alloy
High strength steel
interstices
Carbon
Iron

14. Summary “Sea of electrons” are reason for a metal’s properties
Alloys are mixtures of metals
Substitutional alloys have similar sized elements
Interstitial alloys have different sized elements
Metals are malleable (can be flattened) and ductile (can be drawn into wires), and have luster (are shiny)