PERIODIC TABLE AND TRENDS
Classification as s, p, d & f block
elements
s-block elements: In groups 1 and 2 including He the
last electron enters the s-orbital of the valence shell
are called s-block elements. (14 s-block elements).
p-block elements: In groups 13–18 the last electron
enters the p-orbitals of the valence shell are called
p-block elements.
d-block elements: There are three complete series
and one incomplete series of d-block elements.
1st or 3d transition series which contains ten elements
(atomic numbers 21–30 (21Sc – 30Zn)).
2nd or 4d-transition series which contains ten elements
(atomic numbers 39 – 48 (39Y – 48Cd)).
3rd or 5d transition series also contains ten elements
(atomic numbers 57 and 72 – 80 (57La, 72Hf –
80Hg)).
4th or 6d transition series which is incomplete at
present and contains only nine elements.
The element, Z = 111 has not been discovered so far.
Thus, in all there are 39 d-block elements.
f-Block elements: are called inner-transition
elements. The f-subshell of the anti-penultimate is
being progressively filled up.
Two series of f-block elements each containing 14
elements.
The 14 elements from 58Ce – 71Lu in which 4
f-subshell is being progressively filled up are called
lanthanides or rare elements.
Similarly, the 14 elements from 90Th – 103Lr in
,which 5 f-subshell is being progressively filled up are
called actinides.
Building Orbital Diagrams
The aufbau principle is applied – electrons are always placed
in the lowest energy sublevel available.
The exclusion principle states that each orbital may contain a
maximum of 2 electrons, which must have opposite spins.
H (Z = 1) 1s1
He (Z = 2) 1s2
1s
↑↓
1s
↑
Figure
A vertical orbital diagram for the Li ground state.
Increasing energy
1s
2s
3s
4s
5s
6s
7s
2p
, 3p
4p
5p
6p
3d
4d
5d
7p
6d
4f
5f
Review of Electron
Configuration
Atomic Size
The atomic radius is one half of the distance between the nuclei of
two atoms of the same element when the atoms are joined.
Why do these trends exist?
Atom size increases down a group because you
keep moving to a new shell of electrons.
It decreases across a period because you keep
adding protons to the nucleus, which has a
bigger effect than adding an electron.
The extra charge on the nucleus which draws the
electrons inward resulting in smaller size for the
atoms.
Classification as s, p, d & f block
elements
s-block elements: In groups 1 and 2 including He the
last electron enters the s-orbital of the valence shell
are called s-block elements. (14 s-block elements).
p-block elements: In groups 13–18 the last electron
enters the p-orbitals of the valence shell are called
p-block elements.
d-block elements: There are three complete series
and one incomplete series of d-block elements.
1st or 3d transition series which contains ten elements
(atomic numbers 21–30 (21Sc – 30Zn)).
2nd or 4d-transition series which contains ten elements
(atomic numbers 39 – 48 (39Y – 48Cd)).
3rd or 5d transition series also contains ten elements
(atomic numbers 57 and 72 – 80 (57La, 72Hf –
80Hg)).
4th or 6d transition series which is incomplete at
present and contains only nine elements.
The element, Z = 111 has not been discovered so far.
Thus, in all there are 39 d-block elements.
f-Block elements: are called inner-transition
elements. The f-subshell of the anti-penultimate is
being progressively filled up.
Two series of f-block elements each containing 14
elements.
The 14 elements from 58Ce – 71Lu in which 4
f-subshell is being progressively filled up are called
lanthanides or rare elements.
Similarly, the 14 elements from 90Th – 103Lr in
,which 5 f-subshell is being progressively filled up are
called actinides.
Building Orbital Diagrams
The aufbau principle is applied – electrons are always placed
in the lowest energy sublevel available.
The exclusion principle states that each orbital may contain a
maximum of 2 electrons, which must have opposite spins.
H (Z = 1) 1s1
He (Z = 2) 1s2
1s
↑↓
1s
↑
Figure
A vertical orbital diagram for the Li ground state.
Increasing energy
1s
2s
3s
4s
5s
6s
7s
2p
, 3p
4p
5p
6p
3d
4d
5d
7p
6d
4f
5f
Review of Electron
Configuration
Atomic Size
The atomic radius is one half of the distance between the nuclei of
two atoms of the same element when the atoms are joined.
Why do these trends exist?
Atom size increases down a group because you
keep moving to a new shell of electrons.
It decreases across a period because you keep
adding protons to the nucleus, which has a
bigger effect than adding an electron.
The extra charge on the nucleus which draws the
electrons inward resulting in smaller size for the
atoms.
