Electronic configuration properties and common compounds of Group 16 elements
It is interesting to note that certain elements behave like oxygen. In other words, these elements exhibit properties and trends similar to those of oxygen. The members of such a collective group are known as Group 16 elements. Let us see the similarities between oxygen and the other members of this group. We shall also understand why oxygen is an important member of this group.
For convenience sake, we can call this group as the chalcogen family. This family consists of elements found in group 16 of the periodic table. It is essential to remember that periodic tables are an arrangement of elements with similar properties. The chalcogen family is placed under the oxygen classification. Now, these chalcogens are considered as the leading group 16 elements. The elements in this group are – oxygen, sulphur, selenium, tellurium, and polonium. Ref Fig.1.
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What are Chalcogens?
Chalcogens is the name given to periodic table group 16 elements or V1. This group consists of oxygen, sulphur, selenium, tellurium, and polonium. When we call them elements, it is essential to note that oxygen is a gas while other group members are solids. Oxygen and Sulphur are available in pure form while other elements occur as ions in metal ores. O and S form oxides and sulphides.
All elements of this group have isotopes with varying stability. The elements of this group and their compounds vary in their toxicity. O and S are essential to all forms of life. Compounds of selenium, tellurium, and polonium can be hazardous. Selenium is a trace element and can cause disorders. Tellurium compounds have not been known to cause a human fatality. Polonium and its compounds are radioactive, extremely toxic, and need to be handled with care.
About Chalcogens
The chalcogens or the oxygen group is placed in column 16 of the periodic table (ref fig 1). It has elements of oxygen, sulphur, selenium, tellurium, and polonium. You may find one more element, livermorium. The chemical symbols for these elements are- O, S, Se, Te, PO, and Lv. The first four elements of this group are known as chalcogens or ore-forming elements. The reason is that a majority of metal ores found in the Earth’s crust are sulphides or oxides.
You know that oxygen is the most freely found element in nature. It forms 20.946 percent of air and 46.6 percent of the world’s mass generally in the form of silicates, carbonates, oxides and sulphates. We need oxygen to breathe.
Group 16 Elements
All group 16 elements are closely related to human life.
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Oxygen – chemical notation of oxygen is O. It is a colourless and odourless gas. We inhale oxygen and exhale carbon dioxide. Trees exhale oxygen. Oxygen combines with many elements to form their oxides.
Sulphur – the chemical symbol for sulphur is S. It is found in combined as well as the isolated state. In seawater, the percentage of sulphur is 0.09. A large amount of sulphur is found in underground deposits.
Selenium is a rare element. Selenium is found in free as well as in combination with heavy metals such as lead, silver, and mercury in some minerals. Selenium is most stable in grey metallic form.
Tellurium is an element that has properties between metals and non-metals. It is one of the rarest stable elements found on earth. It is located in compounds with copper, lead, silver, and gold. Tellurium is also found in a free state.
Polonium is a radioactive element or isotope in the group 16 elements. It has scientific applications for alpha radiations as it is a radioactive element. It is also a rare element.
FAQs on Group 16 Elements in the Periodic Table
1. What are Group 16 elements in the periodic table?
The Group 16 elements, also called the chalcogens, are oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), and livermorium (Lv).
- They belong to Group 16 (VIA) of the periodic table.
- They have six valence electrons with general outer configuration ns2np4.
- They commonly form compounds like H2O, H2S, and SO2.
- The term “chalcogen” means ore-forming elements, as sulfur and oxygen occur in many ores.
2. Why are Group 16 elements called chalcogens?
Group 16 elements are called chalcogens because they are “ore-forming” elements that commonly occur in metal ores.
- The word comes from Greek: chalcos (ore) and genes (forming).
- Many metal ores exist as oxides (e.g., Fe2O3) or sulfides (e.g., ZnS, PbS).
- Oxygen and sulfur play a key role in metallurgy and mineral formation.
3. What is the valence electron configuration of Group 16 elements?
The valence shell electronic configuration of Group 16 elements is ns2np4.
- They have six valence electrons.
- They need two more electrons to complete an octet, so they often form 2− ions like O2− and S2−.
- This configuration explains common oxidation states such as −2, +4, and +6.
4. What are the common oxidation states of Group 16 elements?
The most common oxidation states of Group 16 elements are −2, +4, and +6.
- −2: Seen in hydrides like H2O and H2S.
- +4: Found in compounds like SO2.
- +6: Found in compounds like SO3 and H2SO4.
- Heavier elements show positive oxidation states more frequently due to availability of vacant d-orbitals (except oxygen).
5. How do the physical properties of Group 16 elements change down the group?
Down Group 16, atomic size and metallic character increase, while electronegativity decreases.
- Atomic radius increases from oxygen to polonium.
- Electronegativity decreases down the group.
- Oxygen and sulfur are non-metals, selenium and tellurium are metalloids, and polonium shows metallic character.
- Melting and boiling points generally increase due to stronger intermolecular forces.
6. Why is oxygen different from other Group 16 elements?
Oxygen shows anomalous behavior due to its small size, high electronegativity, and absence of d-orbitals.
- It forms strong O=O double bonds in O2.
- It mainly shows the −2 oxidation state (except in peroxides like H2O2).
- It cannot expand its octet because it lacks vacant d-orbitals.
- It forms extensive hydrogen bonding in compounds like H2O.
7. What are the hydrides of Group 16 elements?
The hydrides of Group 16 elements have the general formula H2E, where E = O, S, Se, Te, or Po.
- Examples include H2O, H2S, H2Se, and H2Te.
- Bond angle decreases down the group (104.5° in H2O).
- Thermal stability decreases from H2O to H2Te.
- Acidity increases down the group (H2O < H2S < H2Se < H2Te).
8. What are allotropes of sulfur?
Sulfur exhibits allotropy mainly in the forms of rhombic sulfur and monoclinic sulfur.
- Both contain S8 ring structures.
- Rhombic sulfur is stable below 96°C.
- Monoclinic sulfur is stable between 96°C and 119°C.
- Sulfur also forms plastic sulfur when molten sulfur is rapidly cooled.
9. How is sulfur dioxide prepared in the laboratory?
Sulfur dioxide (SO2) is prepared in the laboratory by reacting copper with concentrated sulfuric acid.
- Balanced equation: Cu(s) + 2H2SO4(aq) → CuSO4(aq) + SO2(g) + 2H2O(l)
- SO2 is a colorless gas with a pungent smell.
- It acts as a reducing agent and shows acidic nature.
10. What are the important uses of Group 16 elements?
Group 16 elements have wide industrial and biological importance, especially oxygen and sulfur.
- Oxygen (O2): Used in respiration and combustion; example reaction: 2H2(g) + O2(g) → 2H2O(l).
- Sulfur: Used in the manufacture of H2SO4 (sulfuric acid).
- Selenium: Used in photocells and electronics.
- Tellurium: Used in alloys and semiconductors.
