Question

Why is fluorine always assigned an oxidation state of -1 ? What oxidation number is usually assigned to the other halogen elements when they occur in compounds? In an interhalogen compound involving fluorine (such as ClF ), which atom has a negative oxidation state?

Short answer

Fluorine always has an oxidation state of -1 due to its high electronegativity (3.98), which makes it attract an electron from other atoms to achieve a stable electron configuration. The common oxidation states of other halogens (chlorine, bromine, iodine, and astatine) in compounds range from -1 to +7, with variations in different compounds. In the interhalogen compound ClF, fluorine has an oxidation state of -1 due to its high electronegativity, and chlorine has an oxidation state of +1, as it loses one electron to fulfill fluorine's electron requirement.

Step-by-step solution

Oxidation state is a way to keep track of electrons within a molecule or an ion. It is important to understand that electrons are not always shared equally and that electronegativity decides which atom has a greater control over the shared electrons. The atom with higher electronegativity will have a negative oxidation state, while the one with lower electronegativity will have a positive oxidation state. #Step 2: Fluorine's Oxidation State explained#

Fluorine is the most electronegative element, with an electronegativity of 3.98. Due to its high electronegativity, fluorine always attracts an electron from other atoms and forms a single bond sharing one electron each. In doing so, fluorine gains one electron and achieves a stable electron configuration, similar to the nearest noble gas (Neon). Thus, fluorine's oxidation state is always -1. #Step 3: The Oxidation States of Other Halogens#

There are five elements in the halogen group: fluorine, chlorine, bromine, iodine, and astatine. The typical oxidation states for these halogens, when they occur in compounds, are as follows: 1. Chlorine: -1, +1, +3, +5, or +7 2. Bromine: -1, +1, +3, or +5 3. Iodine: -1, +1, +3, +5, or +7 4. Astatine: -1, +1, +3, +5, or +7 Please note that these are the common oxidation states, but there might be exceptions. #Step 4: Interhalogen Compound involving Fluorine's Oxidation State#

An interhalogen compound is a molecule that consists of two or more different halogen atoms. In the case of ClF, chlorine and fluorine are bonded together. Since fluorine is always assigned an oxidation state of -1 due to its high electronegativity, chlorine will have a positive oxidation state. In this particular case, the oxidation state of chlorine will be +1, as it loses one electron to fulfill fluorine's electron requirement. So, in ClF, fluorine has a negative oxidation state of -1, and chlorine has a positive oxidation state of +1.

Key concepts

Electronegativity

Electronegativity refers to the ability of an atom to attract electrons when it is in a compound. It is a key concept in understanding how molecules form and behave.

• A higher electronegativity value means stronger attraction for electrons.
• Electronegativity helps determine how electrons are shared in a bond.
• It plays a crucial role in predicting oxidation states.

For instance, in a compound like ClF, fluorine has a higher electronegativity than chlorine. Because of this, fluorine attracts more electron density towards itself, resulting in a negative oxidation state. Electronegativity serves as a guide for predicting which atom will hold more electrons, impacting the molecule's properties.

Halogens

Halogens are a group of elements located in Group 17 of the periodic table and include fluorine, chlorine, bromine, iodine, and astatine.

• Known for their high reactivity, especially fluorine.
• Used in various chemical reactions to form salts when combined with metals.
• Common oxidation state is -1 in many compounds.

Each halogen has a unique set of oxidation states, but they all follow a similar trend when combined with other elements. When forming compounds with elements of lower electronegativity, halogens often have negative oxidation states, as they tend to gain electrons.

Interhalogen Compounds

Interhalogen compounds consist of two or more different halogen atoms bonded together. These compounds are particularly interesting because they show the diverse bonding possibilities between halogens.

• Examples include ClF, BrCl, and IBr.
• Tend to have unusual physical and chemical properties compared to halogens themselves.
• The most electronegative halogen in the compound will dictate the electron density distribution.

In the ClF compound, for example, fluorine, being more electronegative than chlorine, will attract more electron density, making fluorine slightly negative, while chlorine adopts a positive oxidation state.

Fluorine

Fluorine is incredibly unique due to its status as the most electronegative element on the periodic table.

• Has an electronegativity value of 3.98, the highest of all elements.
• Always adopts an oxidation state of -1, as it never gives up its electron to other elements.
• Forms bonds that are exceptionally strong due to its ability to attract electrons.

Because of its high electronegativity, fluorine commonly forms compounds in which it gains an electron, achieving a stable noble gas configuration, which is a significant reason why it has a consistent oxidation state.

Chemical Bonding

Chemical bonding encompasses the forces that hold atoms together within compounds. Understanding these bonds helps explain how compounds form and behave chemically.

• Includes various types such as ionic, covalent, and metallic bonds.
• Bonds result from the sharing or transferring of electrons between atoms.
• Electronegativity influences the type and strength of a chemical bond.

In a polar covalent bond, like in ClF, electrons are shared unequally due to differences in electronegativity. Since fluorine is more electronegative than chlorine, it pulls electron density towards itself, leading to a partial negative charge on fluorine and a partial positive charge on chlorine. Understanding these concepts is essential for predicting molecular structures and reactions.