Open main menu

Block (periodic table)

  (Redirected from Inner transition metal)

A block of the periodic table is a set of chemical elements predominantly characterised by having their highest energy electrons in the same atomic orbital type. The term appears to have been first used by Charles Janet.[1] Each block is named after its characteristic orbital; thus, the blocks are:

  • s-block
  • p-block
  • d-block
  • f-block

The block names (s, p, d, f and g) are derived from the spectroscopic notation for the associated atomic orbitals: sharp, principal, diffuse, and fundamental.

Contents

Periodic tableEdit

There is an approximate correspondence between this nomenclature of blocks, based on electronic configuration, and groupings of elements based on chemical properties. The s-block and p-block together are usually considered as the main-group elements, the d-block corresponds to the transition metals, and the f-block are the lanthanides and the actinides. However, not everyone agrees on the exact membership of each set of elements, so that, for example the group 12 elements Zn, Cd and Hg are considered as main group by some scientists and transition metals by others, because they are chemically and physically more similar to the p-block elements than the other d-block elements. The group 3 elements are sometimes also considered main group elements due to their similarities to the s-block elements. Groups (columns) in the f-block (between groups 3 and 4) are not numbered.

Helium is from the s-block, with its outer (and only) electrons in the 1s atomic orbital, although its chemical properties are more similar to the p-block noble gases due to its full shell.

Group → 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
↓ Period
1 1
H

2
He
2 3
Li
4
Be

5
B
6
C
7
N
8
O
9
F
10
Ne
3 11
Na
12
Mg

13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4 19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5 37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6 55
Cs
56
Ba
57
La
  72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7 87
Fr
88
Ra
89
Ac
  104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og

  58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
  90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr

s-blockEdit

The s-block is on the left side of the periodic table and includes elements from the first two columns, the alkali metals (group 1) and alkaline earth metals (group 2), plus hydrogen and helium. Helium can be placed in the second group of s block as well as the 18th group of p-block, but most scientists consider it to rest at the top of group 18 i.e. above neon (atomic number 10) as it has many properties similar to the group 18 elements. General valance configration is ns1-2

Most s-block elements are highly reactive metals due to the ease with which their outer s-orbital electrons interact to form compounds. The first period elements in this block, however, are nonmetals. Hydrogen is highly chemically reactive, like the other s-block elements, but helium is a virtually unreactive noble gas.

The s-block elements are unified by the fact that their valence electrons (outermost electrons) are in the s orbital. The s-orbital is a single spherical cloud which can contain only one pair of electrons; hence, the s-block consists of only two columns in the periodic table. Elements in column 1, with a single s-orbital valence electron, are the most reactive of the block. Elements in the second column have two s-orbital valence electrons, and, except for helium, are only slightly less reactive.

p-blockEdit

The p-block is on the right side of the periodic table and includes elements from the six columns beginning with column 13 and ending with column 18. Helium, though being in the top of group 18, is not included in the p-block. General valence configration is ns np1-6.

This contains variety of elements and is the only block that contains all three types of elements: metals, nonmetals, and metalloids. Generally, the p-block elements are best described in terms of element type or group.

The p-block elements are unified by the fact that their valence electrons (outermost electrons) are in the p orbital. The p orbital consists of six lobed shapes coming from a central point at evenly spaced angles. The p orbital can hold a maximum of six electrons, hence there are six columns in the p-block. Elements in column 13, the first column of the p-block, have one p-orbital electron. Elements in column 14, the second column of the p-block, have two p-orbital electrons. The trend continues this way until column 18, which has six p-orbital electrons.

d-blockEdit

The d-block is on the middle of the periodic table and includes elements from columns 3 through 12. These elements are also known as the transition metals because they show a transitivity in their properties i.e. they show a trend in their properties in simple incomplete d orbitals. Transition basically means d orbital lies between s and p orbitals and shows a transition from properties of s to p.

The d-block elements are all metals which exhibit two or more ways of forming chemical bonds. Because there is a relatively small difference in the energy of the different d-orbital electrons, the number of electrons participating in chemical bonding can vary. This results in the same element exhibiting two or more oxidation states, which determines the type and number of its nearest neighbors in chemical compounds.

The d-block elements are unified by mostly having one or more chemically active d-orbital electrons. The d-orbitals can contain up to five pairs of electrons; hence, the block includes ten columns in the periodic table.

f-blockEdit

The f-block is in the center-left of a 32-column periodic table but in the footnoted appendage of 18-column tables. These elements are not generally considered as part of any group. They are often called inner transition metals because they provide a transition between the s-block and d-block in the 6th and 7th row (period), in the same way that the d-block transition metals provide a transitional bridge between the s-block and p-block in the 4th and 5th rows.

The known f-block elements come in two series, the lanthanides of period 6 and the radioactive actinides of period 7. All are metals. Because the f-orbital electrons are less active in determining the chemistry of these elements, their chemical properties are mostly determined by outer s-orbital electrons. Consequently, there is much less chemical variability within the f-block than within the s-, p-, or d-blocks.

The f-block elements are unified by mostly having one or more of their outermost electrons in an f-orbital. The f-orbitals can contain up to seven pairs of electrons; hence, the block includes fourteen columns in the periodic table.

See alsoEdit

ReferencesEdit

  1. ^ Charles Janet, La classification hélicoïdale des éléments chimiques, Beauvais, 1928