What is the Difference Between Halogens and Pseudohalogens?

🆚 Go to Comparative Table 🆚

The main difference between halogens and pseudohalogens lies in their composition and location in the periodic table. Halogens are chemical elements in group 17 of the periodic table, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Pseudohalogens, on the other hand, are chemical compounds composed of various elements that have similar chemical characteristics to halogens. Some examples of pseudohalogens include cyanide (CN-), isocyanide (NCCN), and thiocyanate (SCN-).

Similarities between halogens and pseudohalogens include:

  • Both are reactive chemical species.
  • They can form monobasic acids when combined with hydrogen.
  • Both can add to ethylenic double bond linkages.
  • They can react with alkalis.

Differences between halogens and pseudohalogens include:

  • Halogens are group 17 elements in the periodic table, while pseudohalogens are chemical compounds.
  • Pseudohalogens undergo polymerization and form polymerization series, but halogens have no tendency to undergo polymerization.
  • Pseudohalide ions are stronger coordinating ligands than halide ions, and they can function as ambidentate ligands, while halide ions do not have these properties.

Comparative Table: Halogens vs Pseudohalogens

Halogens and pseudohalogens are both types of chemical compounds, but they have distinct differences. Here is a table comparing their characteristics:

Characteristic Halogens Pseudohalogens
Definition Halogens are group 17 elements in the periodic table, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Pseudohalogens are chemical compounds that have a combination of several chemical elements and exhibit chemical characteristics similar to halogens.
Origin Halogens are natural chemical elements. Pseudohalogens are synthetic compounds.
Chemical Properties Halogens are very reactive and are known as "salt-producing" agents. Pseudohalogens have chemical behavior resembling halogens, such as forming covalent compounds.
Examples Common halogens include fluorine, chlorine, bromine, iodine, and astatine. Common pseudohalogens include cyanide/isocyanide, cyanate/isocyanate, azide, their sulfur analogs such as thiocyanate, and complexes such as tetracarbonyls.

In summary, halogens are natural chemical elements with high reactivity, while pseudohalogens are synthetic compounds with chemical behavior similar to halogens, but they are not halogens themselves.