Basic Introduction
When we enter the world of chemistry as learners and students, we are exposed to a variety of chemical reactions, elements and equations. It is intriguing as we learn more about how various substances in our world react and bond with each other to produce different natural and man-made resources that we use for our living.
One such topic of study in Chemistry is the oxidation states of elements. Let us understand what this means.
Oxidation Process of Group 16 Elements
The elements of Group 16, termed as ore-forming elements belong to the p-block of the periodic table because as their last electron enters into the p-orbital. The group 16 elements are Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te) and Polonium (Po). Out of these, selenium and tellurium are metalloids, polonium is unstable because it is a radioactive element and oxygen and sulphur are non-metals.
Science tells us that the valency of the electrons of the group 16 elements is 6 which in turn means that 2 more electrons will be required to achieve the octet state.
The electronic configuration of group 16 elements is ns2np4.
Oxidation State of Oxygen (O2)
For oxygen, its oxidation state is determined by how many elements it is able to gain or let go of to attain a noble gas configuration. Depending on how stable the compound formation is, an element can have only one oxidation state. It also depends on electronegativity and the electronic configuration of these elements. Electronegativity depends on the ability of the elements to attract electrons towards itself. The smaller, the greater its electronegativity.
Oxygen has high electronegativity. It displays a -2 oxidation state, which means that it gains 2 electrons in most of its metallic oxides. Because oxygen is small and d-orbitals are absent, oxygen does not have space for unpaired electrons. However exceptions include a +2 oxidation state in OF2, +1 oxidation state in O2F2, and -1 oxidation state in hydrogen peroxide (H2O2 ).
Oxidation State of Sulphur
Sulphur is bigger in size. It has an empty d-orbital 3d because of which it can expand its valency. While it has a -2 oxidation state, sulphur also exhibits +2, +4 and +6 oxidation states, out of which +4 and +6 are common oxidation states.
the oxidation state of sulphur is (+II).
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FAQs on Oxidation States of Group 16 Elements
1. H2O has Strong Hydrogen Bonding Whereas H₂Te/H₂S Does not Despite Belonging to the Same Group. Why?
This is attributed to the high electronegativity of oxygen which helps in the formation of H-bond with it. Hydrogen bonds are formed between highly electronegative elements like Fluorine/nitrogen/oxygen and hydrogen. The more is the electronegativity of the element the more will be the strength of the H-bond formation. Oxygen has a higher electronegativity as compared to sulfur and tellurium so sulfur does not form H-bond.
2. What is the Oxidation State of Sulfur and Oxidation State of Oxygen in the Sulfate ion?
SO4-2 is known as the Sulphate Polyatomic Ion.
The oxidation state of sulfur is +6 and the oxidation state of all the four oxygen is -2 in SO4-2.
One can calculate this by the following method-
The sum of all the oxidation states of atoms present in sulfate ion must be -2
Thus Let the oxidation state of sulfur be x
x + 4*(-2)= -2
x= 8-2
∴ x=+6
The oxidation state of oxygen can also be calculated by putting the oxidation state of sulfur as +6.
Using this method one can easily find oxidation states of different elements in polyatomic ions.
3. What is meant by oxidation state?
The state of oxidation of an atom is also defined as its oxidation number. In a chemical compound, it represents the amount of electrons an atom has lost which in turn shows us the extent of oxidation. It can also be understood as the hypothetical charge if a particular atom’s bond with other atoms were totally ionic in nature.
4. What is the oxidation state of selenium and tellurium?
Selenium and tellurium are metalloids. Their oxidation states are -2, +2, +4 and +6 respectively.
5. What is the oxidation state of polonium?
Polonium is an unstable, radioactive metal. It has +4 and +2 oxidation states. It has a half-life of 13.8 days which means that it reduces to half its quantity in 14 days. It is actually a decay product of uranium and thorium. The inert pair effect in polonium’s structure causes the pair of electrons in the outermost s orbital to not participate in the bonding of the electrons. Hence, the +6 oxidation state is not very suitable here or for the lowermost elements in group 16. Because the electronegativity of the elements also decreases as we go down, the stability of the -2 oxidation state also decreases gradually.
6. What are the uses of oxidation?
Oxidation in various systems has different uses. In the biological food ecosystem, it can help remove organic pollutants. Chemically it is used in the process of disinfection to kill bacteria and microbial pathogens. It is also used to treat wastewater of impurities.
7. How can one best prepare for this topic in Chemistry?
As we have noted earlier, Chemistry is a wondrous world of reactions, elements, compounds and equations. It does take a lot of understanding, patience and memorization though. Hence it is advisable to keep Vedantu’s resources such as revision notes, articles and important concepts by your side when you sit to study not only this topic but the subject of Chemistry as a whole. You can also keep a separate book for reactions and equations and note down your doubts to get them solved. Besides, the best way is to keep preparing your own revision notes.