The periodic table is divided into four blocks depending on the type of shells being filled. These are s, p, d, and f block elements that constitute the whole periodic table. The term block was used by Charles Janet for the first time when he introduced his left step periodic table (LSPT). The divisions into the blocks are characterized by their distinctive nature. For example:
- s-block is characterized by highly electropositive metals along with helium and hydrogen.
- p-block is characterized by metals, non-metals, and metalloids of groups 3 to 8.
- d-block is characterized by metals with variable (transition) oxidation states.
- f-block is characterized by Lanthanide and Actinide metals.
A detailed discussion about four blocks of the periodic table i.e. s-block, p-block, d-block, and f-block is given below:
s-Block of Periodic table
The s-block of the periodic table comprises the IA and IIA group metals along with hydrogen (H) and helium (He).
- The elements of group IA except hydrogen are called alkali metals.
- The elements of group IIA are called alkaline earth metals.
The s-block elements are on the left side of the periodic table except for helium. Each row of the periodic table contains two s-block elements.
Properties of s-block elements
Each s-block element has valence electrons in the s-orbital. The alkali metals in the s-block contain one electron in their valence shell. While the alkaline earth metals contain two electrons. The s-block elements lose their electrons to form mono-positive and di-positive ions.
The electronic configuration of alkali metals is shown below:
The electronic configuration of alkaline earth metals is shown below:
Almost all the s-block elements are present in combined states. Some most important minerals of s-block elements are:
- Beryl – Be3Al2(SiO3)6
- Gypsum – CaSO4.2H2O
- Phosphorite – Ca3(PO4)2
- Borax – Na2B4O7.10H2O
- Carnallite – KCl.MgCl2.6H2O
Melting and boiling points
The s-block elements have low melting and boiling points due to their large sizes. Similarly, their melting and boiling points decrease down the group due to an increase in size.
The melting and boiling points of alkali metals are shown below:
The melting and boiling points of alkaline earth metal are shown below:
The s-block elements contain one or two electrons in their outermost shell. These electrons can be easily removed due to the low value of ionization potential. Therefore, they can form mono-positive and dipositive cations. The reactivity of s-block elements increases down the group. This is because of the increase in atomic size and increasing ease with which an electron can be removed from the outermost shell.
The s-block elements are good conductors of heat and electricity. This is due to the presence of the loosely held valence electron which can easily be removed.
When s-block elements are exposed to the flame, they impart characteristic colors. This is because they undergo an electronic transition in the visible region of the spectrum.
Colors of the alkali metals
- Li (crimson red)
- Na (yellow)
- K (violet)
- Rb (red-violet)
- Cs (blue)
Colors of the alkaline earth metals
- Be ( no color)
- Mg (no color)
- Ca (brick red)
- Sr (crimson red)
- Ba (apple green)
Applications of s-block elements
There are the following applications of the s-block elements:
- s-block elements are good reducing agents because they are good metals.
- They are used in photoelectric cells due to their low ionization energies. For example, cesium, etc.
- The compounds of these elements are used in medicine. For example, potassium iodide is used in the treatment of syphilitic diseases, etc.
- Flash photography uses magnesium as a source of white intense light.
- They are used as a window material for x-ray and other spectroscopic techniques.
- Armor plates imply lithium and other metals.
- Some elements like lithium are used in the production of electrochemical cells.
p-Block of Periodic table
The last six groups (3A – 8A) of the periodic table are included in the p-block. They are on the right side of the periodic table. The p-block contains metals, non-metals, and metalloids altogether.
Properties of p-block elements
The general electronic configuration of p-block elements except helium is ns2 np1-6. They have all valence electrons in the p-orbital.
The electronic configuration of some p-block elements is shown below:
- Boron is present in traces in soil. It is always found in a combined state with oxygen.
- Aluminum, like other metals, is not present in the free state, it is always found in the form of compounds. It is the third most abundant element in the earth’s crust.
- In nature, carbon is found in both states (free or combined).
- Silicon is found in the rocks, either in the form of silicates or silica.
- Nitrogen is present in a free state in the air. It forms about 78% by volume of the air.
- The halogens are not present in the free state. They are always found in the form of compounds.
- Noble gases are found in traces in free states in the environment, as they are inert.
Melting and boiling points
The p-block of the periodic table contains a variety of elements. For example, metals, non-metals, and metalloids. These elements have different physical states, therefore they show different melting and boiling points.
The melting and boiling points of halogens are shown below:
Metallic and non-metallic character
As discussed above, p-block contains metals, non-metals, and metalloids.
The metallic character increases down the group due to an increase in size and decreases as we move from left to right in a period. Similarly, the nonmetallic character decreases in a group while increasing in a period.
The metals of p-block are good conductors of electricity while non-metals are bad conductors. The conductivity of metalloids is intermediate between metals and nonmetals.
Applications of p-block elements
- p-block elements are generally used in medicine. For example, borax is used in the treatment of mouth sores, etc.
- Boron is used in soaps and cleaners, etc.
- Alum is used in the waterproofing of materials.
- Diamond, an allotropic form of carbon is used in hard drilling and breaking stones. Other allotropes of carbon are also widely used.
- Graphite is used as electrode material and in the manufacturing of lead pencils, etc.
- Silicon is used in the preparation of hard types of alloys.
- Ammonia is used in fertilizer and for ice-making, etc.
d-Block of Periodic table
The d-block elements are also called transition elements. They are present between the s and p-block of the periodic table and their properties are also in between the s and p-block elements.
The transition elements are divided into the different series:
- 1st transition series starts with the scandium.
- 2nd transition series starts with the yttrium.
- 3rd transition series starts with the lanthanum.
- 4th transition series start with actinium, although some elements of the lanthanum and actinium series are excluded from the d block elements category.
Properties of the d-block elements
The general electronic configuration of the d-block elements is (n-1)d1-10ns1-2. The d-block elements have stability associated with the half-filled and fully filled d-subshell.
For example, in chromium metal, one electron from the s-subshell is shifted to the half-filled d-subshell. Similarly in copper, one electron from the s-subshell is shifted to the d-subshell to fill it completely.
The d-block elements can form alloys with one another and with other metals.
- Brass (Cu-Zn)
- Bronze (Cu-Zn-Sn)
- Alnico (Al, Ni, Co)
- Solder (Sn, Pb, Cd, Zn, in)
- Cast iron (C, Si, Mn, S, P), etc
Melting and boiling points
The transition metals have strong binding forces between their atoms. Therefore, they have high melting and boiling points. This property makes these elements usable for high-temperature conductance.
The d-block elements exhibit variable oxidation states. This is because of the involvement of the d-electrons. The highest oxidation state of the transition metals is +8 shown by the ruthenium and osmium. Manganese shows the most variable oxidation state till +7 which corresponds to different natural colors of this metal from green to pink and brown/black.
The d-block elements have a variety of colors. This is due to the involvement of the d-orbital.
The colors of some transition metals ions are shown below:
Application of d-block elements
- In Haber’s process, iron is used as a catalyst for the formation of ammonia.
- Titanium is used in the manufacturing of airships.
- The d-block elements are used as catalysts for many reactions. For example, nickel is used for the hydrogenation reaction, etc.
- Ziegler-Natta (TiCl4+Al(CH3)3) complex is used in the polymerization of ethene into polythene.
- Manganese dioxide is used in dry batteries, etc.
- Tungsten has been used as a bulb filament for centuries.
- Titanium being the only metal acceptable by our body is used for making artificial joints and screws to fix artificial teeth, etc.
- Iron and its alloy steel, are the most widely used metals in the industrial sector.
f-Block of Periodic table
The f-block elements are called inner transition metals. This is because their properties are in between the s and d-block of the periodic table. This block contains most of the elements named after scientists.
The f-block elements are divided into two series:
“The f-block elements in which 4f orbital is in process of filling is known as lanthanides”
“The f-block elements in which 5f orbital is in process of filling is known as actinides.”
Properties of f-block elements
The electronic configuration of the lanthanides is [Xe] 4fn 6s2 except for Ce, Gd, and Lu. This is because in these elements 5d orbital is singly occupied. As compared to the lanthanides, actinides make greater use of the d and f orbitals.
In lanthanides and actinides, the f-orbital is not involved in the chemical bonding. Therefore, they have mostly a +3 oxidation state. In case of lanthanides +2 and +4 are also exhibited as stable electronic configurations while actinides use +2 to +7 oxidation states.
Melting and boiling points
The f-block elements have high melting and boiling points. This is because of the presence of strong metallic bonds between their atoms.
Application of f-block elements
- Most of these elements are primarily used in nuclear reactors. For example, plutonium, uranium, etc.
- They are used in the treatment of many diseases. For example, thorium is used in the treatment of cancer.
- Lanthanide oxides are used in the glass cleaning industry.
- Thorium oxide is a well-known catalyst for many reactions.
- Lanthanum alloys are used for making heat-resistant materials.
Periodic table by Blocks
Charles Janet introduced a new concept of arrangement of elements according to the blocks of elements they are put in. His model of the periodic table is known as the left step periodic table (LSPT).
What Is an elemental block?
“On the basis of completion of a particular subshell, elements with same subshell electronic configuration are called a block of the elements.”
Which elements fall into which block?
- The elements in which the s-orbital is in process of filling lie in the s-block.
- The elements in which the p-orbital are in process of filling fall into the p-block.
- The elements in which the d-orbital is in process of filling lie in the d-block.
- The elements in which the f-orbital is in process of filling fall into the f-block.
What are the four blocks of the periodic table based on electron configuration?
There are four blocks of the periodic table, based on the subshell which is in the process of completion in electronic configuration. These are named s, p, d, and f blocks.
What are s-block and p-block elements?
S and p block elements are called representative elements. This is because their outer shells are incomplete. They get the nearest noble gas configuration by losing, gaining, or sharing electrons.
How many f block elements are there in the periodic table?
There are twenty-eight f-block elements. The first 14 elements lie in the lanthanides series. While the other are fall in the actinide series.
What is the full form of s p d and f in the blocks of the Periodic Table?
The full form of the blocks of the periodic table is as follows:
- s stands for sharp
- p stands for principal
- d stands for diffuse
- f stands for fundamental
They all correspond to the azimuthal quantum numbers.
How many groups are there in the p-block of the periodic table?
The p block of the periodic table contains six groups. These are 13, 14, 15, 16, 17, and 18 groups of the periodic table.
- Inorganic chemistry – sixth edition By Duward Shriver, Mark Weller, Tina Overtone, Jonathan Rourke, and Fraser Armstrong.
- Inorganic chemistry By Muhammad Zafar Iqbal (University of Punjab, Pakistan)