Question

A free radical a. is a positively charged ion. b. is an atom with one unpaired electron in its outer shell. c. is a stable atom that is not bonded to another atom. d. can cause considerable cellular damage. e. both b and d.

Short answer

The correct answer is (e) both (b) and (d).

Step-by-step solution

Identifying the attributes of a free radical

In chemistry, a free radical is an atom, ion, or molecule that has an unpaired valence electron. With some exceptions, these unpaired electrons make free radicals highly chemically reactive.

Consider the implications of free radicals

Due to their reactivity, free radicals can cause significant cellular damage. This is especially true in the context of biology, where they can damage parts of cells such as proteins, DNA, and cell membranes.

Choosing the appropriate option

Given the attributes and implications of free radicals described in Steps 1 and 2, we find that options (b) 'is an atom with one unpaired electron in its outer shell.' and (d) 'can cause considerable cellular damage.' are both correct.

Key concepts

Unpaired Electrons

In the world of chemistry, free radicals are notable for possessing unpaired electrons. But what exactly does this mean? Imagine an electron as a tiny charged particle spinning around an atom's nucleus in an orbit or shell. Normally, electrons come in pairs. However, in free radicals, one electron is left unpaired, causing an imbalance.
Because of this imbalance, free radicals become highly reactive. They rapidly seek out other electrons to pair with, often initiating chain reactions. This quest for paired stability drives their behavior. By understanding unpaired electrons, it becomes clear why free radicals are unpredictable and can lead to various chemical reactions.

Cellular Damage

When free radicals roam freely within biological systems, their high reactivity can result in significant residential damage, particularly at the cellular level. How exactly does this happen? Let's dive in.
Free radicals often attack vital cell components such as proteins, DNA, and cell membranes in their hunt for electrons.

• Proteins: They affect protein structures, altering or impairing their function.
• DNA: Damage to DNA can lead to mutations, signaling errors, or even cell death.
• Cell membranes: When compromised, the integrity and function of the membranes are affected, impacting overall cell health.

This cellular assault contributes to various health issues ranging from premature aging to chronic diseases.

Chemical Reactivity

Chemical reactivity is a defining characteristic of free radicals, largely due to their unpaired electrons. When considering chemical interactions, reactivity refers to the tendency of substances to engage in chemical changes and form new substances.
Free radicals, propelled by their unstable electron configuration, tend to participate in reactions spontaneously and vigorously. This can lead to:

• Oxidation: The process of losing electrons, often damaging other molecules.
• Initiation of chain reactions: A single radical can react, producing products that also include free radicals, thereby amplifying their effect.

The intense nature of their reactivity is why antioxidants, substances that neutralize radicals, are so crucial in limiting cellular damage.

Biology Impact

The impact of free radicals extends beyond chemistry into the realm of biology, affecting various biological processes and health outcomes. Understanding this impact begins with acknowledging their role in oxidative stress.
Oxidative stress occurs when there's an imbalance between free radical production and the body's ability to counteract their ill effects, usually via antioxidants. This stress can lead to:

• Chronic diseases: Conditions like cancer, heart disease, and neurodegenerative disorders have been linked to oxidative stress.
• Aging: Free radicals accelerate the aging process by damaging cells and tissues.
• Health and wellness: Continuous oxidative stress can impair bodily functions and defenses, reducing overall health and wellness.

In summary, while free radicals are just a piece of the puzzle, their biological impact is vast, influencing how our bodies function and age.