Periodic table spdf blocks

Classification of Elements and Periodicity in Properties

homework assignment help is most useful online help portal for the students that providing all Online s-p-d-f Block Elements assignment help Services.In the long form of the periodic table, elements are grouped into four main blocks, purely on the basis of electronic configurations. Elements are grouped in blocks 's', 'p', 'd' and 'f' depending on the nature of orbital(s) into which the last electron of the atom enters.

 

 

Location of the four blocks of elements s, p, d, f in the long form periodic table

The 's' block elements

's' block elements, (except helium) are those in which the valence-shell is the 'ns' orbital and where the last electron enters into the 's' orbital of the outer element. The general outer electronic configuration of such elements is either ns¹or ns². The 's' block elements belong to group 1 and 2 of the long form periodic table. They are situated on the left side of the table.

The main characteristics of the 's' block elements are:

Characteristics

• The general outer electronic configurations of 's' block elements are ns^1-2 as all inner shells are already full.
• The 's' block elements are either all alkali metals like Li, Na, K, Rb, Cs and Fr, as in group 1 (having ns¹ outer electronic configuration) or alkaline Earth metals like Be, Mg, Ca, Sr, Ba and Ra, as in group 2 (having ns² outer electronic configurations).
• The 's' block metals are soft and have a low melting and boiling point.
• The metals are very active. They are highly electropositive and lose their valence electrons to form monovalent or divalent cation. For example,

and

• Being highly electropositive, these elements lose electrons readily and are strong reducing agents.
• The 's' block elements mostly form ionic compounds like NaCl, KCl, CaCl₂ etc.

The 'p' Block Elements

'p' block elements are those in which the outer electronic configuration is of the type ns² np¹ to ns² np⁶ and where the last electron enters into any of the outermost 'p' orbitals. These elements belong to groups 13 to 18 of the long form of periodic table and are situated on the right hand side of the table.

The main characteristics of the 'p' block elements are:

Characteristics

• The general outer electronic configurations of 'p' block elements are ns² np^1-6 as all inner shells are already full.
• The 'p' block elements include metals, non-metals and metalloids. Typical examples are Carbon, Nitrogen, Oxygen, Sulphur, Halogens etc.
• These elements enter into chemical combinations by losing, gaining or sharing the valence electrons. The noble gas elements show no reactivity because their outermost shells are completely filled (ns² np⁶).
• The 'p' block elements mostly form covalent compounds. Halogens however form ionic compounds with 's' block metals.

The 'd' Block Elements

'd' block elements are those in which the added electron goes into one of the 'd' orbitals. These elements have valence electrons in both their outermost and penultimate shells (second outermost) and have a general outer electronic configuration of (n - 1) d^1-10 ns^1-2.

The penultimate shell in these elements is expanded from 8 to 18 by the inclusion of ten 'd' electrons. It is for this reason that these elements are called 'd' block elements. Thus, 'd' block elements are those, which in their elemental or combined forms have partially filled 'd' orbitals. They are also referred to as transition elements.

'd' block elements belong to groups 3 to 12 of the long form of periodic table and are situated in the middle of the table between 's' block and 'p' block elements.

All 'd' block elements are classified into four transition series, namely:

3d series in the 4^th period having 10 elements

4d series in the 5^th period having 10 elements

5d series in the 6^th period having 10 elements

6d series in the 7^th period having incomplete elements.

The main characteristics of the 'd' block elements are:

Characteristics

• 'd' block elements have valence electrons in both their outermost and penultimate shells. Valence electrons belonging to the outermost shell or both shells may take part in a chemical reaction. Accordingly, more than one oxidation state can be shown by the same element; this is termed as variable oxidation states.
• Examples: Fe²⁺ and Fe³⁺ ,Cu⁺ and Cu²⁺etc.
• 'd' block elements exhibit transitional behaviour intermediate between highly reactive electropositive alkali metals and the covalent compound forming elements.So they are called as transition elements.
• These elements are metals having high melting and boiling points .
• Most 'd' block elements form coloured salts.
• 'd' block elements, their ions and compounds, are generally paramagnetic. There are one or more unpaired electrons present in their atoms or ions.
• Most of these transition elements are good catalysts.

Properties of 'd' block elements in a period

Because of their characteristic electronic configuration, the properties of transition elements ('d' block elements) in any period do not differ much from each other (unlike nontransition elements from the same period). The electronic configuration of transition elements can be written as: (n - 1) d^x ns^y where, x = 1 to 10 and y = 1, 2.

This indicates that:

• The number of electrons in the outer shell 'ns' is invariably 1 or 2.
• The electronic configuration of transition elements differ from one an other only in the number of electrons in the 'd' orbitals of the (n - 1)^th shell.

The 'f' Block Elements

The 'f' block elements are those, which in their elemental or ionic forms have partially filled 'f' orbitals. The differentiating (last) electron enters 'f' orbitals, which lie inner to the second outermost (penultimate) shell. Thus these elements are also known as inner-transition elements.

There are two series of 'f' block elements, each having 14 elements. Lanthanides (atomic number 58 - 71) are those inner-transition elements in which 4 'f' orbitals are progressively filled. Actinides (atomic number 90 - 103) are those elements in which 5 'f' orbitals are progressively filled.

The 'f' block elements are placed at the bottom of the long form of periodic table in the form of two rows. Most actinides are radioactive.

The general outer electronic configuration of 'f' block elements is, (n - 2) f^1-14 (n - 1) d^0-1 ns²

The main characteristics of the 'f' block elements are:

Characteristics

• 'f' block elements are metals having high melting and boiling points.
• These elements exhibit variable oxidation states: the most common oxidation state being 3+.
• These elements form coloured salts as their salts absorb light from certain visible wavelengths.
• Actinides ('5f' series) are radioactive elements.

Elements can also be classified according to their chemical behaviour (as apart from electronic configurations and similar properties).

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