Difference Between S and P Block Elements

Key Difference – S vs. P Block Elements

The key difference between s and p block elements can be best explained using their electronic configuration. In the s block elements, the last electron fills to the s subshell and in p block elements, the last electron fills to the p subshell. When they form ions; s block elements remove their electrons from outermost s subshell easily whereas p block elements accept electrons to the p subshell or remove electrons from the p-subshell. Some elements in the p-group form positive ions removing electrons from the outermost p-subshell and some elements (the most electronegative elements) form negative ions accepting an electron from others. When you consider the chemical properties, there is a significant difference between s and p block elements; this is basically due to the electron configuration.

What are S-block Elements?

S-block elements are the chemical elements in group I and group II in the periodic table. Since s subshell can accommodate only two electrons, these elements usually have one (group I) or two (group II) electrons in the outermost shell. The elements in group I and II are shown above in the table.

2 Li Be
3 Na Mg
4 K Ca
5 Rb Sr
6 Cs Ba
7 Fr Ra

 IA Alkali metals
 II A Alkaline earth metals

All the elements in s-block form positive ions and they are very reactive.

Difference Between S and P Block Elements

The placement of the S-block Elements in the Periodic Table

What are P-block Elements?

 P-block elements are the elements whose last electron fills into p subshell. There are three p-orbitals; each orbital can accommodate two electrons, making the total of six p-electrons. Therefore, p-block elements have one to six p-electrons in their outermost shell. P-block contains both metals and non-metals; in addition there are some metalloids too.

  13 14 15 16 17 18
2 B C N O   F Ne
3 Al Si P S Cl Ar
4 Ga Ge As Se Br Kr
5 In Sn Sb Te I Xe
6 Tl Pb Bi Po At Rn

Key Difference - S vs P Block Elements

What is the difference between S and P block Elements?

Common Electron Configuration:

S-block Elements: S-block elements have the common electron configuration of [noble gas]ns1 (for group I elements) and [noble gas]ns2 (for group II elements).

P-block Elements: P-block elements have the common electron configuration of [noble gas]ns2 np1-6. But, helium has 1s2 configuration; it is a special situation.

Oxidation States:

S-block Elements: S-block elements do not show multiple oxidation states like p-block elements. For example, the group I elements show +1 oxidation state and group II elements show +2 oxidation state.

P-block Elements: Unlike the s-block elements, p-block elements have a common oxidation state for their respective group in the periodic table and some other additional oxidation states depending on the stability of the ion.

Group 13 14 15 16 17 18
General electron configuration ns2np1 ns2np2 ns2np3 ns2np4 ns2np5 ns2np6
1st member of the group Be C N O F He
Common oxidation number +3 +4 +5 -2 -1 0
Other oxidation states +1 +2, -4 +3, -3 +4, +2, +3,+5, +1, +7 -


S-block Elements: In general, all the s-block elements are metals. They are shiny, good electrical and heat conductors and easy to remove electrons from valence shell. They are the most reactive elements in the periodic table.

P-block Elements: Most of the p-block elements are non-metals. They have low boiling points, poor conductors and difficult to remove electrons from the outermost shell. Instead, they gain electrons. Some of the non-metals are solids (C, P, S, Se) at room temperature while some are gases (Oxygen, Nitrogen). Bromine is a non-metal, and it is a liquid at room temperature.

In addition, p-block contains some metallic elements; aluminum (Al), gallium (Ga), indium (In), tin (Sn), thallium (Tl), lead (Pb), and bismuth (Bi).


Image Courtesy:

1. “Periodic table (polyatomic)” by DePiep  [CC BY-SA 3.0] via Commons

2. “Periodic table blocks spdf (32 column)” by User: DePiep [CC BY-SA 3.0] via Commons