Occurrence of p-Block Elements: In the long form of the periodic table (modern periodic table), the elements have been classified into four blocks: \({\rm{s}},{\rm{ p}},{\rm{ d}}\), and \({\rm{f}}\) depending upon the subshell in which the last electron enters. The modern periodic table has \(7\) periods and \(18\) groups. The elements belonging to groups \(13\) to \(18\), belong to \({\rm{p}}\)-block elements. In this article, Occurrence of \({\rm{p}}\)-Block Elements, you will know the elements of each group from groups \(13 – 18\), their percentage occurrence, minerals, ores, and much more.

What are p-block Elements?

The elements in which the last electron enters into the \({\rm{p}}\)-subshell of their outermost energy level are called \({\rm{p}}\)-block elements. The elements belonging to groups \(13\) to \(18\) constitute \({\rm{p}}\)-block elements. There are six groups of \({\rm{p}}\)-block elements in the periodic table because a \({\rm{p}}\)-subshell has three degenerate \({\rm{p}}\)-orbitals, each accommodating two electrons. Elements such as boron, carbon, nitrogen, oxygen, fluorine, and helium head these groups.

These involve the addition of one \({\rm{(n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{1}}}{\rm{)}}\), two \(\left( {{\rm{n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{2}}}} \right)\), three \(\left( {{\rm{n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{3}}}} \right)\), four \(\left( {{\rm{n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{4}}}} \right)\), five \(\left( {{\rm{n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{5}}}} \right)\), and six \(\left( {{\rm{n}}{{\rm{s}}^{\rm{2}}}{\rm{n}}{{\rm{p}}^{\rm{6}}}} \right)\), electrons respectively in \({\rm{p}}\)-orbitals while \({\rm{s}}\)-orbitals are already filled. Boron, carbon, nitrogen, oxygen, fluorine, and neon are the first members of these groups.

Electronic Configuration of p-block Elements

The general electronic configuration of \({\rm{p}}\)-block elements is \({\rm{n}}{{\rm{s}}^2}{\rm{n}}{{\rm{p}}^{1 – 6}}\), where n varies from \(2\) to \(7\). The inner core of the electronic configuration may, however, differ. The difference in the inner core of elements results in the variation in their physical properties such as atomic and ionic radii, ionisation enthalpy, electron gain enthalpy, electronegativity, etc., and chemical properties.

Oxidation State of p-block Elements

The maximum oxidation state of \({\rm{p}}\) block elements is numerically equal to the total number of valence electrons (i.e., the sum of the \({\rm{s}}\) and \({\rm{p}}\) electrons) or the group number minus \(10\). This is also called the group oxidation state. The number of possible oxidation states increases towards the right side of the periodic table. For example, group \(13\) show an oxidation state of \(+3\) while those of group \(14\) show the highest oxidation state of \(+4\) and so on.

Occurrence of Group 13 Elements

Group \(13\) of the periodic table consists of the elements boron \(\left( {\rm{B}} \right)\), aluminium \(\left( {\rm{Al}} \right)\), gallium \(\left( {\rm{Ga}} \right)\), indium \(\left( {\rm{In}} \right)\), and thallium \(\left( {\rm{Tl}} \right)\). Boron is non-metal, and the remaining elements are metals.

Boron is a fairly rare element, and it occurs to a very small extent (0.0001%) by mass in the earth’s crust. It occurs in two allotropic forms \({}_5^{10}{\rm{B}}\left( {19\% } \right)\) and \({}_5^{11}{\rm{B}}\left( {81\% } \right)\). It occurs as borates or orthoboric acid. The main ores of boron are borax \(\left( {{\rm{N}}{{\rm{a}}_2}\;{{\rm{B}}_4}{{\rm{O}}_7}.10{{\rm{H}}_2}{\rm{O}}} \right)\), kernite \(\left( {{\rm{N}}{{\rm{a}}_2}\;{{\rm{B}}_4}{{\rm{O}}_7}.4{{\rm{H}}_2}{\rm{O}}} \right)\), colemanite \(\left( {{\rm{C}}{{\rm{a}}_2}{{\rm{B}}_6}{{\rm{O}}_{11}}.5{{\rm{H}}_2}{\rm{O}}} \right)\).

Aluminium is the third most abundant element by weight \(\left( {8.1\% } \right)\) found in the earth’s crust after oxygen \(\left( {46.6\% } \right)\) and silicon \(\left( {27.7\% } \right)\). The important minerals of aluminium are bauxite \(\left( {{\rm{A}}{{\rm{l}}_2}{{\rm{O}}_3} \cdot 2{{\rm{H}}_2}{\rm{O}}} \right)\), cryolite \(\left( {{\rm{N}}{{\rm{a}}_3}{\rm{AI}}{{\rm{F}}_6}} \right)\), orthoclase \(\left( {{\rm{KAI}}{{\rm{S}}_3}{{\rm{O}}_8}} \right)\), corundum \(\left( {{\rm{A}}{{\rm{l}}_2}{{\rm{O}}_3}} \right)\) and beryl \(\left( {{\rm{B}}{{\rm{e}}_3}{\rm{A}}{{\rm{l}}_2}{\rm{S}}{{\rm{i}}_6}{{\rm{O}}_{18}}} \right)\).

Gallium, indium, and thallium are less abundant than aluminium. The highest concentration of gallium \(\left( {0.1 – 1\% } \right)\) is found in the rare mineral germanite, a complex of sulphides of zinc, copper, germanium, and arsenic.

Traces of indium are found in the sulphide ores of zinc, while thallium is found in the sulphide ore of lead.

Occurrence of Group 14 Elements

Group \(14\) elements include carbon \(\left( {\rm{C}} \right)\), silicon \(\left( {\rm{Si}} \right)\), germanium \(\left( {\rm{Ge}} \right)\), tin \(\left( {\rm{Sn}} \right)\), lead \(\left( {\rm{Pb}} \right)\) and the recently discovered element, ununquadium \(\left( {\rm{Uuq}} \right)\), which is radioactive.

Carbon is the seventeenth most abundant element by weight in the earth’s crust. It occurs in the native state in the form of coal, graphite, and diamond. In a combined state, it occurs widely as metal carbonates, hydrocarbons (petroleum), carbohydrates and \({\rm{C}}{{\rm{O}}_2}(0.03\% )\) in air. It is the essential constituent of all living organisms. Naturally, occurring carbon contains three isotopes: \(_6^{12}{\rm{C}},{\mkern 1mu} \,_6^{13}{\rm{C}}\) and \({}_6^{14}{\rm{C}}\).

Silicon is the second \(27.7\%\) most abundant element (next to oxygen) by weight in the earth’s crust. It widely occurs in silica, i.e., \({\rm{Si}}{{\rm{O}}_2}\) (sand and quartz) and a wide variety of silicate and clays. Germanium occurs in traces \(\left( {1.5{\rm{ ppm}}} \right)\) and is mainly recovered from flue dust arising from rusting of zinc ores.

The natural abundance of tin and lead is \(2{\rm{ ppm}}\) and \(13{\rm{ ppm}}\), respectively. Tin occurs mainly as tinstone or cassiterite \(({\rm{Sn}}{{\rm{O}}_2})\). The principal ore of lead is galena (PbS) which is often associated with zinc blende (ZnS). Other ores of lead are anglesite \(\left( {{\rm{PbS}}{{\rm{O}}_2}} \right)\) and cerussite \(\left( {{\rm{PbC}}{{\rm{O}}_3}} \right)\).

Occurrence of Group 15 Elements

The elements of group \(15\) (pnictogens) of the periodic table are nitrogen \(\left( {\rm{N}} \right)\), phosphorus \(\left( {\rm{P}} \right),\) arsenic \(\left( {\rm{As}} \right)\), antimony \(\left( {\rm{Sb}} \right)\) and bismuth \(\left( {\rm{Bi}} \right)\).

Nitrogen occurs as a diatomic gas \(({{\rm{N}}_2})\). It makes about \(78\% \) by volume of the atmosphere. It is the thirtieth most abundant element in the earth’s crust \(\left( {9{\rm{ ppm}}} \right)\). It occurs as nitrates, i.e., \({\rm{NaN}}{{\rm{O}}_3}\) (Chile saltpetre) and \({\rm{KN}}{{\rm{O}}_3}\) (Indian Saltpetre). Nitrogen is the essential constituent of proteins, amino acids and nucleic acids, which regulate the growth and control the heredity effects in living beings.

Phosphorus is a very reactive element, and hence it does not occur in a state. It occurs in the minerals of the apatite family, \({\rm{C}}{{\rm{a}}_9}{\left( {{\rm{P}}{{\rm{O}}_4}} \right)_6} \cdot {\rm{Ca}}{{\rm{X}}_2}\) (\({\rm{X}} = {\rm{F}},\,{\rm{Cl}}\) or \({\rm{OH}}\)) like fluoroapatite \(\left( {3{\rm{C}}{{\rm{a}}_3}{{\left( {{\rm{P}}{{\rm{O}}_4}} \right)}_2} \cdot {\rm{Ca}}{{\rm{F}}_2}} \right)\), chloroapatite \(\left( {3{\rm{C}}{{\rm{a}}_3}{{\left( {{\rm{P}}{{\rm{O}}_4}} \right)}_2} \cdot {\rm{CaC}}{{\rm{l}}_2}} \right)\). These minerals are the major components of phosphate rocks.

Phosphorus is an essential constituent of animal and plant matter. It is present in bones as well as in living cells. About 60% of our bones and teeth are \({\rm{C}}{{\rm{a}}_3}{\left( {{\rm{P}}{{\rm{O}}_4}} \right)_2}\) or fluorapatite. Phosphoproteins are present in milk and eggs. It also occurs in nucleic acids (\({\rm{DNA}}\) and \({\rm{RNA}}\)).

The elements arsenic, antimony and bismuth are not very abundant. They mainly occur as sulphides, i.e., arsenopyrite \(({\rm{FeAsS}})\), stibnite \(\left( {{\rm{S}}{{\rm{b}}_2}\;{{\rm{S}}_3}} \right)\) and bismuth glance \(\left( {{\rm{B}}{{\rm{i}}_2}\;{{\rm{S}}_3}} \right)\) as traces in other ores.

Occurrence of Group 16 Elements

Group \(16\) (chalcogens) of the periodic table consists of five elements viz., oxygen \(\left( {\rm{O}} \right)\), sulphur \(\left( {\rm{S}} \right)\), selenium \(\left( {\rm{Se}} \right)\), tellurium \(\left( {\rm{Te}} \right)\) and polonium \(\left( {\rm{Po}} \right)\).

Oxygen is the most abundant of all the elements. It occurs in the states as dioxygen \(\left( {{{\rm{O}}_2}} \right)\) and makes up \(20.46\% \) by volume and \(23\% \) by mass of the atmosphere. Most of the O₂ present in the atmosphere is produced by photosynthesis. It also occurs in the form of ozone \(\left( {{{\rm{O}}_3}} \right)\), an allotrope of oxygen, in the upper atmosphere. Oxygen makes up \(46.6\% \) by weight of the earth’s crust, where it mainly occurs as silicates minerals. It also makes up \(89\% \) of the weight of water in oceans.

Sulphur, on the other hand, occurs less abundantly. It is the sixteenth most abundant element and constitutes \(0.03\) to \(0.1\% \) by mass of the earth’s crust.

In the combined state, it primarily occurs as sulphates such as gypsum \(\left( {{\rm{CaS}}{{\rm{O}}_4} \cdot 2{{\rm{H}}_2}{\rm{O}}} \right)\), Epsom salt \(\left( {{\rm{MgS}}{{\rm{O}}_4} \cdot 7{{\rm{H}}_2}{\rm{O}}} \right)\), baryte \(\left( {{\rm{BaS}}{{\rm{O}}_4}} \right)\) and as sulphides such as galena \(({\rm{PbS}})\), zinc blende \(({\rm{ZnS}})\) and copper pyrites \(\left( {{\rm{CuFe}}{{\rm{S}}_2}} \right)\).

Another major source of sulphur is \({{\rm{H}}_2}{\rm{S}}\) present in natural gas and crude oil. Sulphur also exists in the combined state of living matter and constituent many organic materials such as eggs, proteins, enzymes, hair, etc.

Selenium and tellurium are less abundant than sulphur and occur as selenides and tellurides in sulphide ores. Polonium is even less abundant \(\left( {0.001{\rm{ ppm}}} \right)\) in the earth’s crust, where it occurs as a decay product in thorium and uranium minerals.

Occurrence of Group 17 Elements

Group \(17\) (halogens) of the periodic table consists of five elements: fluorine \(\left( {\rm{F}} \right)\), chlorine \(\left( {\rm{Cl}} \right)\), bromine \(\left( {\rm{Br}} \right)\), iodine \(\left( {\rm{I}} \right)\), and astatine \(\left( {{\rm{At}}} \right)\). Halogens are highly reactive elements and hence do not occur in the state or native. They mainly occur in the combined state in their halide \(({{\rm{X}}^ – })\) salts, although iodine also occurs as an iodate \(\left( {{\rm{IO}}_3^ – } \right)\).

Fluorine occurs as insoluble fluorides to the extent of \(0.07\% \) in the earth’s crust. The chief minerals of fluorine are fluorspar \(\left( {{\rm{Ca}}{{\rm{F}}_2}} \right)\), cryolite \(\left( {{\rm{N}}{{\rm{a}}_3}{\rm{AI}}{{\rm{F}}_6}} \right)\) and fluorapatite \(\left( {{\rm{Ca}}{{\rm{F}}_2} \cdot 3{\rm{C}}{{\rm{a}}_3}{{\left( {{\rm{P}}{{\rm{O}}_4}} \right)}_2}} \right)\).  A small amount of fluorides is also present in the soil, river water, plants, bones, and teeth of animals.

Chlorine is the most abundant of all the halogens and occurs as chloride to the extent of (\(0.14\% \) in the earth crust. The chief sources of chlorine are seawater (\(2.8\% \) by mass), salt wells and salt beds. In salt beds, it mainly occurs as sodium chloride \(({\rm{NaCl}})\), carnallite \(\left( {{\rm{KCl}}.{\rm{MgC}}{{\rm{l}}_2} \cdot 6{{\rm{H}}_2}{\rm{O}}} \right)\) and calcium chloride \(\left( {{\rm{CaC}}{{\rm{l}}_2}} \right)\).

Bromine occurs as bromide to the extent of \(2.5 \times {10^{ – 4}}\% \) in the earth’s crust. It mainly occurs in seawater and salt lakes as bromides of alkali and alkaline earth metals, i.e., \({\rm{NaBr}},\,{\rm{KBr}}\) and \({\rm{MgB}}{{\rm{r}}_2}\).

Iodine occurs to the extent of \(8 \times {10^{ – 5}}\% \) in the earth crust. It mainly occurs in seaweeds as alkaline metal iodides, caliche which is mainly sodium nitrate, contains iodine as sodium iodate \(\left( {{\rm{Nal}}{{\rm{O}}_3}} \right)\).    

Occurrence of Group 18 Elements

Group \(18\) (noble gases) of the periodic table consists of six monatomic gases, i.e., helium \(\left( {{\rm{He}}} \right)\), neon \(\left( {{\rm{Ne}}} \right)\), argon \(\left( {{\rm{Ar}}} \right)\), krypton \(\left( {{\rm{Kr}}} \right)\), xenon \(\left( {{\rm{Xe}}} \right)\) and radon \(\left( {{\rm{Rn}}} \right)\). Except for radon, all other gases are present in the atmosphere in very small quantities in the elemental state, and hence they are known as rare gases of the atmosphere.

Their total percentage in dry air is about \(1\% \) by volume, of which argon is the major component. Helium is the second most abundant element in the universe, although its terrestrial abundance is very low. Helium is also present in natural gas to the extent of \(2\) to \(7\% \). Helium and sometimes neon are also present in small quantities in various radioactive minerals such as Clevite, monazite, pitchblende, etc. Helium, neon and argon are also present in trace amounts in some spring waters.

Summary

The modern periodic table consists of \(118\) elements. These elements are placed in different groups based on the electrons in the valence shell.  In this article, Occurrence of p-Block Elements, you have understood the meaning of the \({\rm{p}}\)-block element, its general electronic configuration, oxidation state. Apart from this, you have explored the different elements of each group, i.e., from groups \(13 – 18\), their percentage occurrence, minerals, ores, etc. This will be helpful in generalising the common properties of elements in each group.

FAQs on Occurrence of p-Block Elements

Q.1. What is the occurrence of p-Block Elements?
Ans: Metals occur in the combined state as oxides, carbonates, sulphides, silicates, halides, sulphates, arsenides, phosphates, etc.
Non-metals occur in the state as well as in the combined state. The non-metals like hydrogen, carbon, nitrogen, oxygen, sulphur and noble gases like helium, neon, argon, krypton, xenon are found in the states.

Q.2. What type of elements are kept in p-block?
Ans: In p-block, elements like metals, metalloids (semimetals), and non-metals are placed.

Q.3. What is the general electronic configuration of p-block elements?
Ans: The general electronic configuration of \({\rm{p}}\)-block elements is \({\rm{n}}{{\rm{s}}^2}{\rm{n}}{{\rm{p}}^{1 – 6}}\), where n varies from \(2\) to \(7\).

Q.4. What are the p-block elements?
Ans: The elements in which the last electron enters into the \({\rm{p}}\)-subshell of their outermost energy level are called \({\rm{p}}\)-block elements.

Q.5. What are the characteristics of p-block elements?
Ans: The \({\rm{p}}\)-block elements are placed in groups \(13 – 18\). It includes metal, metalloid, and non-metals. In these valences, electrons enter into the \({\rm{p}}\)-subshell. These show several oxidation states except fluorine and inert gases.

Q.6. Why are they called p-block elements?
Ans: Because in these elements the last electron enters into the \({\rm{p}}\)-subshell of their outermost energy level.

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