p block consists of groups 13 to 18 in the periodic table, having the general electronic configuration as ns²np¹–⁶. This special group has metals, non-metals, and metalloids, as well as different elements. This block contains halogens, noble gases, carbon, nitrogen, and oxygen as their essential elements. The elements in this block form covalent compounds and exist in different oxidation states. The chemical behaviour is strongly affected by the inert pair effect, ionization energy, and electronegativity of the specific elements. The mentioned properties thus produce a broad spectrum of chemical and physical characteristics. Emphasis on the p-block elements is important in this era because of their diversity in characteristics and critical uses, which proves to be the basis for several chemical, industrial, and biological processes.
The boron family, Group 13 elements (B, Al, Ga, In, Tl), shows a range of physical properties. Boron is a non-metal, while others are metals. Their melting and boiling points vary, with boron having the highest melting point due to its covalent structure. The atomic and ionic sizes increase down the group, and density also increases except for irregularities like gallium.
Anomalous behaviour of Boron means it deviates from the rest of its group due to its small size, high ionization energy, and absence of d-orbitals. Unlike metals in its group, boron forms covalent bonds and shows non-metallic properties. It also forms compounds like borates and boric acid, which are unique to it.
The Boron family reacts with acids, bases, and halogens. Boron forms covalent compounds, while others can form ionic ones. For example, aluminium reacts with acids and bases, showing its amphoteric nature. The tendency to form stable +3 oxidation states decreases down the group due to the inert pair effect.
Diborane (B2H6) is a covalent hydride of boron with a unique structure featuring three-center two-electron bonds (banana bonds). Diborane is a colorless, flammable gas used as a reducing agent and in organic synthesis. It reacts with water, releasing hydrogen and forming boric acid.
Orthoboric acid (H3BO3) is a weak monobasic acid that forms by dissolving borax in water. It is used as an antiseptic and in glass manufacturing. It has a layered structure with hydrogen bonding and acts as a Lewis acid by accepting hydroxide ions.
Borax is a key boron compound has the chemical formula Na2B4O7⋅10H2O. Borax is used in glass and ceramics production, detergents, and as a flux in metallurgy. On heating, borax gives a bead test, forming a characteristic glassy bead of boric oxide.
Boron and silicon exhibit a diagonal relationship due to their similar electronegativity and ionic sizes. Both form covalent compounds, hydrides, and oxides with acidic properties. They also share structural similarities in borates and silicates.
Group 14 elements (Carbon family) exhibit trends in metallic and non-metallic behaviour. Carbon and silicon are non-metals, while others are metals. The +4 oxidation state is more stable in lighter elements, whereas the +2 state becomes predominant in heavier ones due to the inert pair effect.
Allotropes of Carbon are diamond, graphite, and fullerenes. Diamond has a tetrahedral structure, making it the hardest natural substance, while graphite has a layered structure with delocalized electrons, making it a good conductor of electricity.
Carbon monoxide (CO) is a colorless, toxic gas with strong reducing properties. Carbon dioxide (CO2) is a non-toxic gas, essential for photosynthesis. Both play crucial roles in biological and industrial processes.
Silicates are compounds containing silicon-oxygen tetrahedra. They form the majority of Earth's crust and are found in minerals like quartz and feldspar. Their structures vary from simple to complex, influencing their properties and uses.
Silicon dioxide (SiO2) is also known as silica, is a major component of sand. It forms a network structure and is used in glassmaking, electronics, and construction. It is chemically inert and resistant to high temperatures.
Silicones are synthetic polymers with silicon-oxygen backbones and organic side groups. They are used in lubricants, sealants, and medical implants due to their flexibility, water resistance, and thermal stability.
Group 15 elements (Nitrogen family) show trends in non-metallic to metallic behaviour down the group. Nitrogen forms diatomic molecules with a triple bond, while heavier elements exhibit metallic and amphoteric properties.
Dinitrogen is prepared by fractional distillation of liquid air or by thermal decomposition of ammonium dichromate. Dinitrogen is inert due to the strong triple bond and is used in fertilizers, explosives, and as a refrigerant.
Ammonia is prepared by the Haber process. It is a colorless gas with a pungent odor, soluble in water, and acts as a weak base. Ammonia is widely used in fertilizers and cleaning products.
Nitrogen forms a variety of oxides with diverse oxidation states. Oxides of Nitrogen are important in environmental chemistry as they contribute to pollution and acid rain.
Phosphorus exists in several allotropes, including white, red, and black phosphorus. White phosphorus is highly reactive and stored under water, while red phosphorus is less reactive and used in matchstick production.
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P-block elements consist of elements from group 13 to group 18. These elements have various properties and characteristics that are important to learn. These p-block elements are completely different from each other. Some members of this group are metals like aluminum, some are metalloids like silicon and germanium, and rest are non-metals like oxygen, chlorine, etc.
Electronic Configuration
The general electronic configuration of p-block elements is given as follows:
Group 13 elements: ns2 np1
Group 14 elements: ns2 np2
Group 15 elements: ns2 np3
Group 16 elements: ns2 np4
Group 17 elements: ns2 np5
Group 18 elements: ns2 np6
Metallic Character
In the p-block series, the elements are classified into various categories based on their metallic character. The metallic character of the elements increases as we move down the group. There are some elements that are between the metallic and non-metallic characters, known as metalloids. Group 17 elements are purely non-metals known as halogens. Group 18 elements are known as noble gases.
Atomic Radii
As we move down the group, there is always the addition of one more shell; due to this, the radius of the elements always increases in moving down the group. But as we move from left to right, the atomic size decreases. This is because, from left to right in the same period, no extra shell is added,d but the nuclear charge is increased and thus the size is decreased
Ionization Enthalpy
The ionization energy of p-block elements increases from left to right because of the effective nuclear charge on the outer electrons increases. But from top to bottom, this ionization energy decreases as the size of the atom increases, due to which the influence of the nucleus on the electrons decreases, and thus it is easy to remove the electron from the outermost shell.
Electronegativity
The electronegativity of p-block elements increases from left to right as the effective nuclear charge increases. From the bottom, the electronegativity decreases because of increased atomic size and lesser influence of the nucleus.
Melting and Boiling Points
The melting and boiling points of all the p-block elements increase as we move down the groups. This is because of the fact that as we move down the group, the atomic size of elements increases due to which the melting and boiling points increase.
Oxidation States
The p-block elements show variable oxidation states. Generally, the value of their oxidation states is negative but when bonded with more electronegative atoms then they also exhibit positive oxidation states. The maximum oxidation state shown by the atom is equal to the number of valence electrons. The oxidation states of different elements are shown below:
Magnetic properties
Almost all the elements of the periodic table are diamagnetic in nature. Some elements like iodine, Astatine, Radon, and Polonium are non-magnetic. Only Tin is the element that is paramagnetic.
Color of p-block elements
These elements have various real-life applications that we observe around us on a daily basis. Some of them are mentioned below.
This chapter is a part of inorganic chemistry. It is completely theory-based and very easy to learn; no need to memorize any formulas.
Before reading this chapter, first, you must have the basic knowledge of the chapter - periodic classification of elements.
You must also learn why there are some elements like Boron and Carbon show anomalous behavior with respect to other elements in their group.
The rest of this complete chapter is very simple, just be regular and be consistent in your practice.
First, you must finish the class XI and XII NCERT textbook and solve each and every example and unsolved question given in it. Then for advanced level preparation like JEE and NEET, you must follow O.P. Tandon. You must definitely solve the previous year's papers. Meanwhile, in the preparation, you must continuously give mock tests for the depth of knowledge. Our platform will help you to provide a variety of questions for deeper knowledge with the help of videos, articles, and mock tests.
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Halogens (F₂, Cl₂): Toxic and corrosive; require ventilation.
Arsenic (As), Lead (Pb): Carcinogenic; need proper disposal.
Boron Hydrides (e.g., B₂H₆): Highly flammable.
The first elements (e.g., B, C, N, O, F) exhibit unique properties due to their small size, high electronegativity, and absence of d-orbitals. Examples include carbon’s catenation and nitrogen’s diatomic (N≡N) stability.
Metalloids, such as silicon and germanium, possess properties that are intermediate between metals and nonmetals. They are vital in the semiconductor industry, which is essential for electronics, solar cells, and various other applications.
Group 13 (Boron group): Aluminum (lightweight alloys), Boron (semiconductors, borosilicate glass).
Group 14 (Carbon group): Silicon (electronics), Carbon (organic chemistry, nanomaterials).
Group 15 (Nitrogen group): Nitrogen (fertilizers), Phosphorus (matches, detergents).
Group 16 (Chalcogens): Oxygen (medical, combustion), Sulfur (sulfuric acid production).
Group 17 (Halogens): Chlorine (disinfectants), Fluorine (Teflon, refrigerants).
The inert pair effect refers to the reluctance of the ns² electrons (in heavier p-block elements like Pb, Tl, and Bi) to participate in bonding, making lower oxidation states (e.g., Pb²⁺, Tl⁺) more stable than higher ones (e.g., Pb⁴⁺, Tl³⁺).
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