What Are the Oxidation States of Group 16 Elements Trends Examples and Exceptions
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 and Variable Valency of Group 16 Elements
1. What are the common oxidation states of Group 16 elements?
The most common oxidation states of Group 16 elements (O, S, Se, Te, Po) are −2, +2, +4, and +6.
- The −2 oxidation state is the most common and is shown in compounds like H2O, H2S, and Na2S.
- The +4 and +6 oxidation states are typical for sulfur, selenium, and tellurium, as seen in SO2 (+4) and SO3 (+6).
- Oxygen mainly shows −2 but can show −1 in peroxides like H2O2 and +2 in OF2.
2. Why does oxygen mainly show a −2 oxidation state?
Oxygen mainly shows a −2 oxidation state because it gains two electrons to complete its octet and achieve a stable noble gas configuration.
- Electronic configuration: 1s22s22p4.
- By gaining two electrons, it forms O2−.
- Example: In H2O, each H is +1, so O must be −2.
3. Why does sulfur show +4 and +6 oxidation states but oxygen does not?
Sulfur shows +4 and +6 oxidation states because it can expand its octet using vacant 3d orbitals, whereas oxygen cannot expand beyond eight electrons.
- Sulfur electronic configuration: [Ne]3s23p4.
- In SO2, sulfur is +4.
- In SO3 or H2SO4, sulfur is +6.
4. What is the oxidation state of oxygen in peroxides and superoxides?
In peroxides, oxygen has an oxidation state of −1, while in superoxides, it is −1/2.
- Example of peroxide: H2O2 (each O = −1).
- Example of superoxide: KO2 (each O = −1/2).
5. What is the highest oxidation state shown by Group 16 elements?
The highest oxidation state shown by Group 16 elements (except oxygen) is +6.
- Sulfur shows +6 in SO3 and H2SO4.
- Selenium shows +6 in SeO3.
- Tellurium shows +6 in TeO3.
6. How do you calculate the oxidation state of sulfur in H2SO4?
The oxidation state of sulfur in H2SO4 is +6.
- Hydrogen = +1 each → 2 × (+1) = +2
- Oxygen = −2 each → 4 × (−2) = −8
- Let sulfur = x
- x + 2 − 8 = 0
- x − 6 = 0 → x = +6
7. Why is the −2 oxidation state more stable down Group 16?
The −2 oxidation state becomes less stable down Group 16 due to decreasing electronegativity and increasing atomic size.
- Oxygen strongly favors −2 because of high electronegativity.
- Down the group (S, Se, Te), the tendency to gain electrons decreases.
- Heavier elements more commonly show positive oxidation states like +4 and +6.
8. What oxidation states does oxygen show in OF2?
In OF2, oxygen has an oxidation state of +2.
- Fluorine is always −1 in compounds.
- Let oxygen = x.
- x + 2(−1) = 0
- x − 2 = 0 → x = +2
9. What are some examples of +4 oxidation state in Group 16 elements?
The +4 oxidation state is common for sulfur, selenium, and tellurium in their dioxides.
- SO2 (sulfur dioxide)
- SeO2 (selenium dioxide)
- TeO2 (tellurium dioxide)
10. How do oxidation states of Group 16 elements vary down the group?
The oxidation states of Group 16 elements shift from predominantly −2 in oxygen to more frequent +4 and +6 states in heavier elements.
- Oxygen: mainly −2, rarely positive.
- Sulfur: −2, +4, +6 common.
- Selenium and tellurium: +4 and +6 become increasingly stable.
- Polonium: shows +2 and +4 due to increased metallic character.
