The Periodic Table

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 2p

n = 1l = 0

ml = 0

n = 2l = 0

ml = 0

n = 2l = 0

ml = 0 ml = 1ml = -1

H: 1s1

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

1s 2s 2p

n = 1l = 0

ml = 0

n = 2l = 0

ml = 0

n = 2l = 0

ml = 0 ml = 1ml = -1

He: 1s2

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

1s 2s 2p

n = 1l = 0

ml = 0

n = 2l = 0

ml = 0

n = 2l = 0

ml = 0 ml = 1ml = -1

Li: 1s2 2s1

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

1s 2s 2p

n = 1l = 0

ml = 0

n = 2l = 0

ml = 0

n = 2l = 0

ml = 0 ml = 1ml = -1

Be: 1s2 2s2

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

Hund’s rule: maximum number of unpaired electrons is the lowest energy arrangement.

1s 2s 2p

C: 1s2 2s22p2

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

1s 2s 2p

N: 1s2 2s22p3

O: 1s2 2s22p4

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

1s 2s 2p

F: 1s2 2s22p5

Ne: 1s2 2s22p6

s- and p-orbitals

‘Aufbau’ Principle: filling orbitals

Na: 1s22s22p63s1 or [Ne]3s1

Mg: 1s22s22p63s2 or [Ne]3s2

P: [Ne]3s23p3

Ar: [Ne]3s23p6

d-orbitals

E

1s

2s

3s

4s

2p

3p

3d

Due to deeper penetration of s-orbitals, 4s lies lower in energy than 3d

d-orbitals

K: 1s22s22p63s23p64s1 or [Ar]4s1

Ca: [Ar]4s2

Sc: [Ar]4s23d1

V: [Ar]4s23d3

Cr: [Ar]4s13d5

Co: [Ar]4s23d7

Cu: [Ar]4s13d10

Zn: [Ar]4s23d10

Ga: [Ar]4s23d104p1

Kr: [Ar]4s23d104p6

Beyond the d-orbitals

lanthanides

actinides

‘s’-groups ‘p’-groups

d-transition elements

f-transition elements

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 electronsp: 6 electrons

d: 10 electronsf: 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 elementsElements 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:

uraniumneptunium

plutonium

Ur92

Np93

Pu94

Exotic elements

Md

101Mendelevium

Es

99Einsteinium

Bh

107BohriumLives for only 10 ms!

Uun

110

No name yet! Barbarium?

Atomic Radius

The atomic radius r is usually determined from the distances between atoms in covalent bonds.

How big is an atom?

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 RadiusArrange the following sets of atoms in order of increasing size:

Sr, Se, Ne :

Fe, P, O :

Ne(10) < Se(34) < Sr(38)

O(8) < P(15) < Fe(26)

Li+(3) < Na+(11) < Rb+(37)

Arrange the following sets of ions in order of increasing size:

Na+, Rb+, Li+ :

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 EnergyS(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 EnergyIonization 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 EnergyFirst ionization energies

Ionization energy increases across the period from left to right.

Ionization energy decreases going down a group

General trends:

Ionization EnergyA closer look…..

B: 1s22s22p1

O: 1s22s22p4

New subshell, electron is easier to remove.

First paired electron in 2p orbital: repulsion.

Understanding a groupAtoms in a group have the same valence electron configuration and share many similarities in their chemistry.

Group 1A: Alkali metals

KNaLi

Cs

Understanding a group

Trends down the group reflect periodic changes in mass, volume and charge.

Group 1A: Alkali metals

Periodic Table in Brief

Periodic Table Redux

Periodic Table Redux