What are elements F, Cl, Br, I and At commonly known as?
Halogens
Identifying Elements F, Cl, Br, I, and At
The question asks for the common name given to the elements Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At).
Let's look at these elements and their position in the periodic table.
Understanding Halogens
These five elements are located in Group 17 of the periodic table. Group 17 elements are collectively known by a special name.
- Fluorine (F)
- Chlorine (Cl)
- Bromine (Br)
- Iodine (I)
- Astatine (At)
Elements in Group 17 are known as Halogens. The term "halogen" comes from Greek words meaning "salt-producer", as these elements readily form salts when they react with metals.
Evaluating Other Options
Let's consider why the other options are not correct for these elements:
- Actinoids: Actinoids are a series of 15 metallic chemical elements from actinium (atomic number 89) through lawrencium (atomic number 103). They are typically found in the f-block of the periodic table. Fluorine, Chlorine, Bromine, Iodine, and Astatine are not part of this series.
- Transition elements: Transition elements are generally considered to be the elements in the d-block of the periodic table. They are located between Group 2 and Group 13. Fluorine, Chlorine, Bromine, Iodine, and Astatine are in Group 17 (p-block elements), not the d-block.
- Rare earth elements: This term commonly refers to the lanthanide series (elements 57-71) and sometimes includes scandium and yttrium. They are mostly found in the f-block. Fluorine, Chlorine, Bromine, Iodine, and Astatine are not rare earth elements.
Conclusion on Element Classification
Based on their location in Group 17 of the periodic table and their characteristic chemical properties, the elements F, Cl, Br, I, and At are commonly known as Halogens.
| Group Number | Common Name | Example Elements |
|---|---|---|
| 1 | Alkali Metals | Li, Na, K |
| 2 | Alkaline Earth Metals | Be, Mg, Ca |
| 17 | Halogens | F, Cl, Br, I, At |
| 18 | Noble Gases | He, Ne, Ar, Kr, Xe, Rn |
Revision Table: Key Element Groups
| Group/Series Name | Typical Location | Key Elements |
|---|---|---|
| Halogens | Group 17 (p-block) | F, Cl, Br, I, At |
| Actinoids | f-block (Period 7) | Ac, Th, Pa, U...Lr |
| Transition elements | d-block (Groups 3-12) | Fe, Cu, Ag, Au... |
| Rare earth elements | f-block (Lanthanides) | La, Ce, Pr...Lu |
Additional Information on Halogens
Halogens are highly reactive nonmetals (except Astatine, which is a metalloid and radioactive). They have 7 valence electrons and tend to gain one electron to form a −1 ion. Their reactivity generally decreases down the group from Fluorine to Iodine.
Properties of Halogens:
- Exist as diatomic molecules ($\text{F}_2, \text{Cl}_2, \text{Br}_2, \text{I}_2$) in their elemental form.
- Have high electronegativity.
- Form acidic solutions when their hydrides dissolve in water (e.g., HCl in water forms hydrochloric acid).
- Used in various applications, such as disinfectants (Chlorine), lighting (Iodine), and plastics (Fluorine, Chlorine).
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