Chemical Properties of Group 15 Elements
In chemistry, groups of elements refer to different columns of elements in the periodic table. There are in total 18 groups that are numbered in the periodic table from left to right. The f-block column of the periodic table is still not numbered as a group.
Out of the 18 numbered groups, we are going to talk about group 15. Group 15 consists of the p-block elements (the block in the periodic table is an arrangement or set of elements on the basis of their valence electrons). The p-block is situated on the right-hand side of the table. The group 15 elements include nitrogen, phosphorus, arsenic, antimony, and bismuth.
The members of group 15 show similar patterns in their electronic configuration, especially in their outermost shell. All these elements have 2 electrons in their subshell, and all of their outermost shells consist of 5 electrons.
The two most important elements of this group are Nitrogen and Phosphorus. Nitrogen, which occurs in a free state as a gas that is diatomic, constitutes more than 70% of the volume of air. Phosphorus is an element of life- its forms are present in our RNA and DNA. It is also present in bone marrows.
The Trends in Chemical Reactivity of the Group 15 Elements
Here we will discuss the trends in chemical reactivity of the group 15 elements, i.e. nitrogen, phosphorus, arsenic, antimony, and bismuth.
Elements of a group in the periodic table have similar patterns in their configuration of electrons. This similarity results in the formation of different trends in the chemical reactivity of the elements. Similarly, the elements of group 15 have a similar electron configuration- all of them have 2 electrons in their subshells and 5 electrons in their outer shells. This leads to the patterning of trends in their reactivity. Like as we go down the group (from Nitrogen to Bismuth), the metallic character of the elements increases and the ionization enthalpy (the amount of energy required to lose an electron) character of the elements decreases.
The covalent character (sharing of electrons) of the atoms decreases as we move down the group.
Group 15 elements are used in forming hydrides (compounds of hydrogen with any other element). Formation of NH3 (Ammonia), BiH3 (Bismuthine), PH3(Phosphine), AsH3 (Arsine), and SbH3 (Stibine) occurs.
Group 15 elements also form Halides (compounds formed with halogen atoms and any element). The halide is usually trihalides and pentahalides, e.g. Phosphorus trichloride (PCl3) and Phosphorous pentachloride (PCl5).
Group 15 elements form oxides like Nitric Oxide, Bismuth Oxychloride, etc. The oxides are formed by the oxidation process (loss of electrons during a reaction) under different oxidation states of p block elements. H2
Since the atomic size increases as we move down, the melting point also gradually increases. Nitrogen has the least melting point in the group, and as we move to Arsenic and Phosphorus, the melting point starts to increase. There is a decrease in the trend from antimony onwards. This occurs because of the loose structure of atoms in the bonding.
The boiling point of the elements regularly increases as we move down, and so does the density of the elements.
Oxidation States of Group 15 Members
The number of electrons in the outermost shell of the group 15 members is 5. In order to make it an octet configuration, it requires 3 more electrons. Therefore, it needs to gain 3 more electrons or share 3 electrons with the help of the covalent bonds. Therefore, the more common oxidation for these elements is the -3 oxidation which means adding 3 more electrons. The tendency to produce the -3 oxidation decreases as we move down the group. This happens because of the increase in metallic character and the atomic size of the elements. -3 oxidation state is used by reacting the group 15 members with hydrogen to produce ammonia, phosphane, arsane, stibane, and bismuthine. As we go down the group, these hydrides become more toxic and less stable.
The +3 oxidation and +5 oxidation states occur by sharing electrons. In +3 oxidation, this sharing can occur through covalent bonds, in the case of- nitrogen, arsenic, and phosphorus. E.g. Nitrogen trichloride, phosphorus trichloride, arsenic trichloride, or ionic bonds, in the case of antimony and bismuth. E.g. Antimony trifluoride and Bismuth trifluoride. As we move down the group, the covalency character of the elements decreases.
The +5 oxidation state for nitrogen forms the N2O5. The true +5 oxidation occurs in phosphorus, arsenic, and antimony. Phosphorus even produces oxyhalides.
The Other Oxidation States for Group 15 Elements
Nitrogen can form various oxides under oxidation states +2, +4, and very unstable +6.
Antimony can produce a compound under the oxidation state of +2.
Phosphorus in phosphoric acid has the +1 oxidation state, and in hypo phosphoric acid, it has an oxidation state of +4.
General properties of Group 15
Following are the compounds included in the nitrogen family :
Nitrogen(N)
Phosphorus(P)
Arsenic(As)
Antimony(Sb)
Bismuth(Bi)
The electron configuration of all the elements in group 15 is ns2np3in their outer shell, where n is the principal quantum number.
Periodic Trends
Following are the trends followed by all the Group 15 elements :
Electronegativity: Electronegativity of an atom is the ability of that atom to attract electrons. It decreases down the group.
Ionization Energy: The ionization energy of an atom is the amount of energy it requires to remove an electron from an isolated atom/molecule. It decreases down the group.
Atomic Radii: It increases in size down the group.
Electron Affinity: The ability of an atom to accept an electron is known as electron affinity. It decreases down the group.
Melting Point: It is the amount of energy required to break bonds in order to change a substance to a liquid phase from a solid phase. It increases down the group.
Boiling Point: It is the amount of energy required to break bonds in order to change a substance to a phase from the liquid phase. It increases down the group.
Metallic Character: It refers to the level of reactivity of the metal. It increases down the group.
FAQs on Oxidation State of Group 15 Elements
1. What are the Oxidation States of All the Elements of Group 15?
The degree of oxidation of an atom in a chemical compound is indicated by its oxidation state. Following are the oxidation states of all the elements of group 15:
Nitrogen(N) : The oxidation states of nitrogen are +5,+3 and -3. It has the highest electronegativity.
Phosphorus(P): The oxidation state of phosphorus is -3.
Arsenic(As): The oxidation states of arsenic are +5,+3,+2,+1, and -3.
Antimony(Sb): Antimony has three oxidation states. They are +3,-3, and +5.
Bismuth(Bi): The oxidation states of Bismuth are +3 and +5.
2. Who Among Group 15 Exhibits the Most Metallic Character?
Bismuth exhibits the most metallic character among all the group 15 elements. Bismuth has oxidation states of +3 and +5. Bismuth has a lot of usages but commonly it is used in medicines and cosmetic products. Out of all the group 15 elements, it has the lowest ionization energy and electronegativity. This means that bismuth is the most metallic among all the group 15 elements. It is obtained as a by-product of refining other metals, which allows other metals to recycle their byproduct into bismuth.
3. Who Among the Group 15 Elements Do Not Show Allotropy?
All of the elements in group fifteen show allotropy(except for Bismuth). There are two allotropic types of nitrogen: alpha nitrogen and beta nitrogen. Phosphorus is found in a variety of allotropic forms. White phosphorus and red phosphorus are the two most important allotropic types.
Yellow, grey, and black are the three most common allotropic forms of arsenic. Antimony is also available in three allotropic forms: yellow, explosive, and metallic.
4. What are the Trends in Melting and Boiling Point in Group 15?
Because of the gradual increase in atomic size, the melting point rises from nitrogen to arsenic. Nitrogen has an extremely low melting point due to its distinct diatomic molecules. The high melting point of arsenic, on the other hand, is due to its huge layered structure with tightly packed layers.
Although the atomic size of arsenic and antimony increases, their melting points decrease. Antimony has a layered structure, also a lower melting point than arsenic due to the free packing of atoms. Furthermore, because of the loose packing of atoms caused by metallic bonding, bismuth has a lower melting point than antimony. The boiling point of bismuth, on the other hand, gradually rises from nitrogen to bismuth.
5. Where Can I Find Notes of the Oxidation State of Group 15 Elements?
Vedantu has all of the notes and questions on group 15 and their oxidation states. Vedantu provides high-quality content to students at no cost. The content is structured in such a way that students can understand it more easily. To access the free content, students must first visit the Vedantu website and register. Students can use Vedantu's mobile app to do the same thing. Vedantu has content related to every subject. Signup for free now to make full use of it.
6. Is Nitrogen Fluoride a True Example of +5 Oxidation State for Group 15 Members?
When compared with the rest of the Group 15, due to the highest electronegativity it possesses, NItrogen is regarded as the most non-metallic of the group. The most common oxides of NItrogen are +5, +3, and -3. The oxyacids and oxides of Nitrogen comprise of nitrogen oxide, nitrogen dioxide, and nitrous oxide, all of which have different practical applications. As far as Nitrogen Fluoride is concerned, it is indeed an example of +5 oxidation state for group 15 members. But this example is only theoretical as the compound has not been synthesized yet. You can use the example of N2O5 also.
7. Are Pnictogens and the Elements of Group 15 One and the Same Thing?
The greek word for suffocation or choking is “Pnico,” now as all the elements of Group 15 produce suffocating effects, they are also known as pnictogens. Group 15 is also known as the Nitrogen family. The elements of this group exhibit similar patterns in the configuration of the electrons. All the components of this group have 5 electrons in the outermost shell, 2 electrons in the s subshell and 3 unpaired electrons in the p subshell. Yes, any element of the group 15 of the periodic table is also called a pnictogen because the elements belong to the nitrogen family or nitrogen group of elements (nitrogen, phosphorus, arsenic, antimony, bismuth and moscovium).
