Transcript The Periodic Table - UCI Department of Chemistry

The Periodic Table
Periodic Table
Dmitri Mendeleev
(1834-1907)
"We could live at the present day without a Plato, but a double number
of Newtons is required to discover the secrets of nature, and to bring life
into harmony with the laws of nature."
Modern Periodic Table
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
n=1
l=0
ml = 0
n=2
l=0
ml = 0
2p
H: 1s1
n=2
l=0
ml = -1 ml = 0
ml = 1
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
n=1
l=0
ml = 0
n=2
l=0
ml = 0
2p
He: 1s2
n=2
l=0
ml = -1 ml = 0
ml = 1
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
n=1
l=0
ml = 0
n=2
l=0
ml = 0
2p
Li: 1s2 2s1
n=2
l=0
ml = -1 ml = 0
ml = 1
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
n=1
l=0
ml = 0
n=2
l=0
ml = 0
2p
Be: 1s2 2s2
n=2
l=0
ml = -1 ml = 0
ml = 1
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
2p
B: 1s2 2s22p1
‘core’
closed
shell
open shell: valence electrons
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
2s
2p
C: 1s2 2s22p2
Hund’s rule: maximum number of unpaired electrons is
the lowest energy arrangement.
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
N: 1s2 2s22p3
O: 1s2 2s22p4
2s
2p
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
1s
F: 1s2 2s22p5
Ne: 1s2 2s22p6
2s
2p
s- and p-orbitals
‘Aufbau’ Principle: filling orbitals
Na: 1s22s22p63s1
or [Ne]3s1
1s22s22p63s2
[Ne]3s2
Mg:
or
P: [Ne]3s23p3
Ar: [Ne]3s23p6
d-orbitals
3d
4s
3p
3s
E
2s
2p
1s
Due to deeper penetration of s-orbitals, 4s lies lower in
energy than 3d
d-orbitals
K: 1s22s22p63s23p64s1
or [Ar]4s1
Co: [Ar]4s23d7
Ca: [Ar]4s2
Cu: [Ar]4s13d10
Sc: [Ar]4s23d1
Zn: [Ar]4s23d10
V: [Ar]4s23d3
Ga: [Ar]4s23d104p1
Cr: [Ar]4s13d5
Kr: [Ar]4s23d104p6
‘s’-groups
Beyond the d-orbitals
d-transition elements
lanthanides
actinides
f-transition elements
‘p’-groups
Aufbau rules
1. Within a shell (n) the filling order is s>p>d>f
2. Within a subshell (l), lowest energy arrangement has
the highest number of unpaired spin (Hund’s rule)
3. The (n+1)s orbitals always fill before the nd orbitals
4. After lanthanum ([Xe]6s25d1), the 4f orbitals are filled
5. After actinium ([Rn]7s26d1), the 5f orbitals are filled
Filled subshells accommodate:
s:
2 electrons
d:
p:
6 electrons
f:
10 electrons
14 electrons
Electron configuration
Give the electron configuration of Zirconium and Tellurium.
Identify the period and the group of the element
Zirconium is in period 5 and is the 2nd element in the d-transition
element group.
Zr: 1s22s22p63s23p64s23d104p65s24d2
or [Kr]5s24d2
Tellurium is in period 5 and is the 4th element in the ‘p’- group.
Te: 1s22s22p63s23p64s23d104p65s24d105p4
or [Kr]5s24d105p4
Exotic elements
Elements with atomic numbers higher than 92 (Uranium)
typically don’t exist in nature and have to be made by
nuclear synthesis
The first synthesized elements were named after the planets:
uranium
neptunium
plutonium
92
93
94
Ur Np Pu
Exotic elements
99
Einsteinium
Es
101
Mendelevium
Md
107
Bohrium
Bh
Lives for only 10 ms!
110
Uun
No name yet!
Barbarium?
Atomic Radius
How big is an atom?
The atomic radius r is usually
determined from the distances
between atoms in covalent bonds.
Atomic radius decreases across a period from left to right
due to increased effective nuclear charge
Atomic radius increases down a group because of the
larger sizes of the orbitals with higher quantum numbers.
Atomic Radius
Atomic Radius
Atomic Radius
Covalent radius is much smaller than the anionic radius.
Atomic Radius
Arrange the following sets of atoms in order of increasing
size:
Sr, Se, Ne :
Ne(10) < Se(34) < Sr(38)
Fe, P, O
O(8) < P(15) < Fe(26)
:
Arrange the following sets of ions in order of increasing
size:
Na+, Rb+, Li+ :
Li+(3) < Na+(11) < Rb+(37)
Cl-, F-, I- :
F-(9) < Cl-(17) < I-(53)
Ionization Energy
Ionization energy is the energy required to remove an
electron from a gaseous atom or ion :
e+
X(g)
X+(g) + e-
S(g)
S+(g) + e-
I1 = 999.6 kJ/mol
1st ionization energy
S+(g)
S2+(g) + e-
I2 = 2251 kJ/mol
2nd ionization energy
S2+(g)
S3+(g) + e-
I3 = 3361 kJ/mol
3rd ionization energy
Ionization Energy
S(g)
S+(g) + e-
I1 = 999.6 kJ/mol
1st ionization energy
S+(g)
S2+(g) + e-
I2 = 2251 kJ/mol
2nd ionization energy
S2+(g)
S3+(g) + e-
I3 = 3361 kJ/mol
3rd ionization energy
S: 1s22s22p63s23p4
Which electrons are removed in successive ionizations?
Electrons in the outer subshells take the least amount of
energy to remove (valence electrons)
It takes about 1•103 kJ/mol to remove successive electrons
from the 3p shell of sulfur.
Ionization Energy
Ionization energies of aluminum:
Al(g)
Al+(g) + e-
I1 = 580 kJ/mol
1st ionization energy
Al+(g)
Al2+(g) + e-
I2 = 1815 kJ/mol
2nd ionization energy
Al2+(g)
Al3+(g) + e-
I3 = 2750 kJ/mol
3rd ionization energy
Al3+(g)
Al4+(g) + e-
I4 = 11,600 kJ/mol
4th ionization energy
Al: 1s22s22p63s23p1
1st electron: 3p valence electron
2nd electron: 3s valence electron
3rd electron: 3s valence electron
4th electron: 2p core electron!
core electrons take much
more energy to remove
Ionization Energy
Ionization Energy
First ionization energies
General trends:
Ionization energy increases across the period from left to right.
Ionization energy decreases going down a group
Ionization Energy
A closer look…..
B: 1s22s22p1
New subshell, electron is easier to remove.
O: 1s22s22p4
First paired electron in 2p orbital: repulsion.
Understanding a group
Atoms in a group have the same valence electron
configuration and share many similarities in their chemistry.
Group 1A: Alkali metals
Li
Na
K
Cs
Understanding a group
Group 1A: Alkali metals
Trends down the group reflect periodic changes in
mass, volume and charge.
Periodic Table in Brief
Periodic Table Redux
Periodic Table Redux