Properties of Metals
Malleable: Can be hammered into sheets
Ductile: Can be drawn into wires
Planes of atoms
are capable of
slipping with
respect to each
other
Close Packed Structures
Electrical Conductors
Thermal Conductors
Collective sharing
of delocalized
valence electrons
Structure vs. Electron Count
Increasing number of electrons per atom
4 valence e−
[Ne] 3s23p2
5 valence e−
[Ne] 3s23p3
6 valence e−
[Ne] 3s23p4
Silicon
4 bonds
(Black) Phosphorous
3 bonds +
1 nonbonding
electron pair
Sulfur
2 bonds +
2 nonbonding
electron pairs
7 valence e−
[Ne] 3s23p5
Chlorine
1 bonds +
3 nonbonding
electron pairs
Increasing coordination number
1
Close Packed Metals
Atoms pack together as closely as possible. In cubic and hexagonal
close packing each atom has 12 closest neighbors.
Density Aluminum = 2.7 g/cm3
Density Silicon = 2.3 g/cm3
Equal bonding to all neighbors (in all directions) which makes it easy
for planes of atoms to slip over one anonther → malleable, ductile
Metallic Bonding
There are not enough valence electrons to go around so they are collectively
shared (kind of like communism but with bonding). We can think of a fixed
lattice of positive metal ions surrounded by a sea of delocalized electrons.
Delocalized electrons can move easily which makes metals good conductors of
electricity and heat
2
Melting Point & Hardness
Group
Melting
Point
Group
Melting
Point
1
2
3
4
5
6
Rb
Sr
Y
Zr
Nb
Mo
39 °C
777 °C
1522 °C
1854 °C
2477 °C
2623 °C
7
8
9
10
11
12
13
Tc
Ru
Rh
Pd
Ag
Cd
In
2157 °C
2334 °C
1964 °C
1554 °C
962 °C
321 °C
156 °C
N2 MO Diagram
σ∗2p
Half filled 2p orbitals –
maximum bonding
π∗2p
π2p
2p orbitals
2p orbitals
σ2p
σ∗2s
2s orbital
2s orbital
σ2s
3
σ∗1s
σ∗1s
1s orbital
1s orbital
1s orbital
σ1s
1s orbital
H-H Distance = 2 Å
σ1s
Splitting between bonding
and antibonding orbitals
decreases as orbital
overlap decreases
H-H Distance = 1 Å
N2 MO Diagram
σ∗2p
Half filled 2p orbitals –
maximum bonding
π∗2p
π2p
2p orbitals
2p orbitals
σ2p
σ∗2s
2s orbital
2s orbital
σ2s
4
Orbital Overlap – Transition Metal s-orbitals
Most
Antibonding
Overlap of ss-orbitals
• s-orbitals are
relatively large
• Stong overlap
• Wide Band
• 1 orbital per atom –
the band holds 2
electrons per atom
Most
Bonding
Orbital Overlap – Transition Metal d-orbitals
Overlap of dd-orbitals
Most
Antibonding
• d-orbitals are
relatively small
• Weak overlap
Metal d-orbitals
Metal d-orbitals
Most
Bonding
• Narrow Band
• 5 orbital per atom –
the band holds 10
electrons per atom
5
Band Diagram – Rubidium (Rb, Tm = 39 °C)
Most
Antibonding
d-band –
narrow, holds
10 electrons
s-band
Wide, holds 2
electrons
Rb 4d-orbitals
Rb 4d-orbitals
Rb 5sorbital
Bonding d-states are
almost empty. Bonding
is relatively weak.
Melting point is low.
Rb 5sorbital
Most
Bonding
Band Diagram – Molybdenum (Mo Tm = 2623 °C)
Most
Antibonding
d-band –
narrow, holds
10 electrons
s-band
Wide, holds 2
electrons
Mo 4d-orbitals
Mo 4d-orbitals
Mo 5sorbital
Bonding d-states are
almost full. Antibonding
is relatively strong.
Melting point is high.
Mo 5sorbital
Most
Bonding
6
Alloys
Substitutional Alloys
Brass (Cu, Zn),
Interstitial Alloys
Steel (Fe, C)
Sterling Silver (Ag, Cu),
White Gold (Au, Pt)
Common Oxidation States of Metals
d-orbitals are filling up, but due to ineffective shielding
they experience a stronger attraction to the nucleus
The +2 oxidation state is common among first row transition metal
metal elements
because it corresponds to emptying the valence s-orbitals,
orbitals, i.e.
Ni: [Ar
Ar] 3d8
[Ar]] 4s23d8 → Ni2+ [Ar]
7
Magnetism
Diamagnetism
No unpaired
electrons
Paragnetism
Ferrognetism
There are unpaired Unpaired electrons line
electrons, but the
up so that they all
directions of the
point in the same
unpaired electrons are
direction
randomly oriented
8