Physical Properties of Group 16 Elements (Chalcogens Family)

Some important physical properties of Group 16 elements are:

• Electronic Configuration
• Atomic/Ionic Radii
• Ionization Enthalpies
• Electron Gain Enthalpies
• Electronegativities
• Metallic Nature
• Melting and Boiling Points

Now, we will study them in detail.

Electronic Configuration

Group 16 elements or elements of the oxygen family have six electrons in their outermost shell. So the general electronic configuration of them is ns², np⁴. Electronic configuration of each member of the oxygen family is,

Atomic/Ionic Radii

Atomic radii or ionic radii of elements increase as they move down the periodic table. The chalcogen with the smallest atomic and ionic radius (excluding livermorium) is oxygen, and the chalcogen with the largest (excluding livermorium) is polonium. The addition of protons and the increase in effective nuclear charge cause elements’ atomic radii to decrease over time. As a result, the atomic radius of oxygen will be much smaller than that of lithium.

Ionization Enthalpies

Ionization Enthalpies of the elements of the oxygen family are less compared to those of the nitrogen family. The general trend of moving down the group from oxygen to polonium, suggests that the ionization enthalpy or potential decreases on moving down the group.

On moving left to right the general trend of the ionization enthalpy suggest that it increases along the period.

Electron Gain Enthalpies

Electron Gain Enthalpies decrease with an increase in the atom’s size. As a result, the electron gain enthalpies of the chalcogens decrease as one moves down the group. It is worth noting that oxygen has a lower negative electron gain enthalpy than sulphur, which can be attributed to the compressed atomic structure of oxygen, which contributes to interelectronic repulsion between the valence electrons and any other approaching electron.

Electronegativities

Electronegativity decreases as one moves down a group due to a variety of factors, including an increase in atomic radius and an increase in electron-electron repulsion. The most electronegative chalcogen is oxygen, and the least electronegative chalcogen is polonium (livermorium not considered).

Metallic Nature

Non-metal elements include oxygen and sulphur. Metalloids include selenium and tellurium. Under normal conditions, polonium has metallic properties. It should be noted, however, that polonium is a radioactive element. 

Melting and Boiling Points

Melting and Boiling points of elements increase as they progress down a group due to the increase in atomic sizes and atomic masses (as a result of increased intermolecular forces of attraction). Among chalcogens, oxygen has the lowest melting and boiling points. The significant difference in the melting and boiling points of sulphur and oxygen can be attributed to the fact that oxygen exists in the atmosphere as a diatomic molecule, whereas sulphur is typically found as a polyatomic molecule.

Note:

• Fluorine is the most electronegative element while Oxygen is the second most electronegative element.
• All the members of group 16 i.e. oxygen family exhibit allotropy.
• Sulphur(S) in the oxygen family show catenation property similar to that of carbon.

Chalcogens are the Group 16 elements of the modern periodic table consisting of 5 elements oxygen, sulphur, selenium, tellurium and polonium. The elements in this group are also known as chalcogens or ore-forming elements because many elements can be extracted from sulphide or oxide ores. The chalcogens are the elements that belong to group 16 of the modern periodic table (or the oxygen family).

In this article, we are going to learn about what are chalcogens, elements under the chalcogen family and their properties in detail.