Question

The element that does not show positive oxidation state is (a) \(\mathrm{O}\) (b) \(\mathrm{N}\) (c) \(\mathrm{Cl}\) (d) \(\mathrm{F}\)

Short answer

Fluorine (F) does not show a positive oxidation state.

Step-by-step solution

Understanding oxidation states

Oxidation state refers to the degree of oxidation of an atom in a compound. A positive oxidation state means an atom has lost electrons, becoming more positive, while a negative oxidation state means an atom has gained electrons, becoming more negative.

Identifying common oxidation states of the given elements

For each element given in the options, identify their common oxidation states. Oxygen (O) typically has a -2 oxidation state, nitrogen (N) can range from -3 to +5, chlorine (Cl) ranges from -1 to +7, and fluorine (F) always has a -1 oxidation state because it is the most electronegative element.

Determining the element that does not show positive oxidation state

Since fluorine is the most electronegative element, it always attracts electrons towards itself and thus, always has a negative oxidation state. Therefore, fluorine does not show a positive oxidation state.

Key concepts

Oxidation State

The concept of oxidation state is central to understanding how elements interact in chemical reactions. It's a way to keep track of electrons in a chemical reaction, particularly in redox reactions where electrons are transferred between species. Oxidation state is often referred to as oxidation number, and it helps chemists discern the electron configuration of an element within a compound.

For instance, when an element like iron (Fe) reacts to form rust, it loses electrons and is said to be oxidized, with an increase in oxidation state. Conversely, oxygen in this reaction gains electrons, reducing its oxidation state. It is essential to note that the oxidation state doesn't necessarily reflect the actual electrical charge on an ion, but it is a useful construct for balancing chemical equations and understanding reactions. It's calculated based on several rules, including the assumption that the more electronegative element in a binary compound is assigned negative oxidation states equivalent to its charge as an anion.

Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons when it forms a chemical bond. This concept was introduced by Linus Pauling, and it is essential for predicting the nature of chemical bonds. Electronegativity values are dimensionless and are typically found on a scale from around 0.7 (least electronegative element: francium) to 4.0 (most electronegative element: fluorine).

Understanding electronegativity allows chemists to predict the polarity of chemical bonds. When two atoms with different electronegativities form a bond, the electrons are not shared equally. The more electronegative atom will attract the shared electrons closer to itself, creating a partial negative charge, while the less electronegative atom becomes slightly positive. This uneven sharing of electrons is what creates polar covalent bonds. Recognizing this trait can also explain why some elements almost exclusively exhibit negative oxidation states: They're so electronegative that they tend to attract electrons rather than lose them.

Chemical Elements

Chemical elements are the building blocks of matter, each with their unique set of protons in their atomic nuclei. These elements form all the compounds and substances we encounter by combining in various ways. Their behavior, including how they bond and their oxidation states, largely depends on their position in the periodic table, which is organized by atomic number and electron configurations.

Elements can be metals, nonmetals, or metalloids, and these categories can influence their typical oxidation states. For instance, metals often have positive oxidation states because they tend to lose electrons, while nonmetals tend to gain electrons, resulting in negative oxidation states. The interaction of elements during chemical reactions is governed by their inherent properties, such as electronegativity and electron affinities, which dictate their tendency to either lose, gain, or share electrons with other elements.