The key difference between halogens and halides is that the halogens are chemical elements having one unpaired electron in their outermost p orbital whereas the halides have no unpaired electrons.
Halogens are the group 7 elements. Since they have an unpaired electron in the p orbitals, the most common oxidation state of halogens is -1 because they can get stable by obtaining one electron. This electron gaining forms a halide. Therefore, halides are the anionic form of halogens.
CONTENTS
1. Overview and Key Difference
2. What are Halogens
3. What are Halides
4. Side by Side Comparison – Halogens vs Halides in Tabular Form
5. Summary
What are Halogens?
Halogens are group 7 chemical elements having 5 electrons in the outermost p orbital. Furthermore, these elements have one unpaired electron in their outermost p orbital. Therefore, it is highly reactive to obtain an electron from outside and become stable. They readily form the anionic form, halide, by obtaining one electron.
Figure 01: Appearance of Halogens. (From left to right: chlorine, bromine, iodine.)
The members of this group are fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and Astatine (At). Furthermore, the reason for giving them the name halogen is that they all can form sodium salts with similar properties. We can see all the phases of matter within this group; fluorine and chlorine are gases in nature, bromine is a liquid and iodine is a solid compound under normal conditions. Astatine is a radioactive element. Moreover, the general electron configuration of these elements is ns2np5.
What are Halides?
Halides are the anionic forms of halogens. Therefore, these chemical species forms when a halogen gains an electron from outside to get a stable electron configuration. Then the electron configuration becomes ns2np6. However, a halide will always have a negative charge. The members of this group include fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatine (At−). The salts having these ions are halide salts. Furthermore, all these halides are colorless and occur in solid crystalline compounds. These solids have a high negative enthalpy of formation. Therefore, this means these solids easily get formed.
There are specific tests from which we can identify the presence of a halide. For example, we can use silver nitrate to indicate the presence of chlorides, bromides, and iodides. That is because, when we add silver nitrate to a solution containing chloride ions, silver chloride precipitate. If we add silver nitrate to bromide containing solution, a creamy silver bromide precipitate forms. For iodide ion containing solutions, it gives a green colored precipitate. But, we cannot identify fluoride from this test since fluorides cannot form precipitates with silver nitrate.
What is the Difference Between Halogens and Halides?
Halogens are the group 7 chemical elements having 5 electrons in the outermost p orbital, including an unpaired electron. Halides are the anionic forms of halogens and do not have any unpaired electron. This is the main difference between halogens and halides. Further, the members of halogen group are fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and Astatine (At). On the other hand, the members of halide group are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatine (At−). Given below is the detailed difference between halogens and halides in tabular form.
Summary -Halogens vs Halides
Halogens are group 7 elements having an unpaired electron at the outer orbital. They form into halides by gaining an electron and becoming stable. Therefore, the key difference between halogens and halides is that the halogens are chemical elements having one unpaired electron in their outermost p orbital whereas the halides have no unpaired electrons.
Reference:
1. “Halide.” Wikipedia, Wikimedia Foundation, 27 June 2018. Available here
2. Christe, Karl, et al. “Halogen Element.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 3 Nov. 2017. Available here
Image Courtesy:
1.’Halogens’By W. Oelen – Science Made Alive: Chemistry, (CC BY-SA 3.0) via Commons Wikimedia