Question

Write the formulas for the methylmercury ion, for two of its common molecular forms, and for dimethylmercury. What is the principal source of exposure of humans to methylmercury?

Short answer

Methylmercury ion: \( \text{CH}_3\text{Hg}^+ \); common forms: \( \text{CH}_3\text{HgCl} \), \( \text{CH}_3\text{HgOH} \); dimethylmercury: \( \text{(CH}_3\text{)}_2\text{Hg} \). Main source: consuming fish and shellfish.

Step-by-step solution

Understanding Methylmercury Ion

The methylmercury ion consists of one mercury atom bonded to one methyl group. Its chemical formula is represented as \( \text{CH}_3\text{Hg}^+ \).

Identifying Common Molecular Forms of Methylmercury

Two common molecular forms of methylmercury include methylmercury chloride and methylmercury hydroxide. Their formulas are \( \text{CH}_3\text{HgCl} \) and \( \text{CH}_3\text{HgOH} \) respectively.

Understanding Dimethylmercury

Dimethylmercury consists of one mercury atom bonded to two methyl groups. Its formula is \( \text{(CH}_3\text{)}_2\text{Hg} \).

Identifying the Principal Source of Human Exposure to Methylmercury

The principal source of human exposure to methylmercury is through the consumption of fish and shellfish. These aquatic organisms accumulate methylmercury from their environment, which can then enter the human food chain.

Key concepts

Dimethylmercury

Dimethylmercury is a chemical compound with a mercury atom bonded to two methyl groups. It is best represented by the chemical formula \( (\text{CH}_3)_2\text{Hg} \). Dimethylmercury is known for its high toxicity and poses significant risks to human health. It is a colorless liquid that is particularly dangerous because it can easily penetrate skin and some types of protective gloves.

• It evaporates quickly, making it hazardous to breathe.
• Even a small amount can be lethal if absorbed through the skin or inhaled.
• It is not commonly used outside of specialized scientific research due to its toxicity.

Due to these dangers, handling dimethylmercury requires careful safety precautions, and its use is generally avoided in routine laboratory settings.

Human Exposure to Methylmercury

When discussing human exposure to methylmercury, it primarily occurs through diet. Consumption of fish and shellfish is the main pathway by which methylmercury enters the human body. Methylmercury forms in aquatic environments, often accumulating in higher concentrations in top predator fish.

• Larger, long-lived fish such as tuna, swordfish, and shark often contain higher levels of methylmercury.
• This process is known as biomagnification, where methylmercury concentrations increase up the food chain.

Once in the human system, methylmercury can affect the nervous system and is particularly harmful to developing fetuses, potentially leading to cognitive deficits and developmental delays.

Chemical Formulas of Methylmercury

The chemical formulas for the methylmercury ion and its common molecular forms are vital for understanding its chemical characteristics. The methylmercury ion is represented as \( \text{CH}_3\text{Hg}^+ \), indicating a single positive charge. Two common molecular forms include:

• Methylmercury chloride (\( \text{CH}_3\text{HgCl} \)).
• Methylmercury hydroxide (\( \text{CH}_3\text{HgOH} \)).

These molecules highlight methylmercury's ability to form different chemical bonds, resulting in diverse chemical properties. Understanding these formulas helps in identifying the physical and chemical behavior of methylmercury, crucial for any scientific investigations involving this compound.

Molecular Forms

Molecular forms of chemical compounds provide insight into their stability and reactivity. For methylmercury, understanding its various molecular forms is essential, as they dictate how the compound interacts with its environment.

• In methylmercury chloride (\( \text{CH}_3\text{HgCl} \)), the chloride ion stabilizes the molecule, making it slightly less reactive.
• Methylmercury hydroxide (\( \text{CH}_3\text{HgOH} \)), on the other hand, can participate in reactions that involve swapping the hydroxide group with other chemical entities.

Both molecular forms play roles in methylmercury’s environmental mobility and bioavailability. Knowledge of these forms aids in grasping how methylmercury persists and spreads in ecosystems.