Problem 18 - Chemistry: An Atoms-Focused Approach

Question

In the following pairs, which element is more abundant in the human body? (a) \(\mathrm{H}\) or \(\mathrm{Si} ;\) (b) Ca or \(\mathrm{Fe} ;\); \(\mathrm{c}\) ) \(\mathrm{N}\) or \(\mathrm{Cr}.\)

Step-by-Step Solution

Answer

Question: For each of the following pairs of elements, determine which is more abundant in the human body: (a) H or Si; (b) Ca or Fe; (c) N or Cr. Answer: (a) H (hydrogen) is more abundant than Si (silicon); (b) Ca (calcium) is more abundant than Fe (iron); (c) N (nitrogen) is more abundant than Cr (chromium) in the human body.

Step 1: Identify the pairs of elements and their abundance in the human body

We are given three pairs of elements to compare: (a) H (hydrogen) and Si (silicon); (b) Ca (calcium) and Fe (iron); and (c) N (nitrogen) and Cr (chromium). Research or refer to a resource such as a biology or chemistry textbook to find the abundance of each element in the human body.

Step 2: Compare the abundance of hydrogen and silicon

The average abundance of hydrogen in the human body is approximately 10% by mass, while the average abundance of silicon is around 0.026%. Comparing these values, it is clear that hydrogen is more abundant in the human body than silicon. Answer for (a): Hydrogen (H) is more abundant than silicon (Si) in the human body.

Step 3: Compare the abundance of calcium and iron

The average abundance of calcium in the human body is approximately 1.5% by mass, while the average abundance of iron is around 0.006%. Comparing these values, it is clear that calcium is more abundant in the human body than iron. Answer for (b): Calcium (Ca) is more abundant than iron (Fe) in the human body.

Step 4: Compare the abundance of nitrogen and chromium

The average abundance of nitrogen in the human body is approximately 2.4% by mass, while the average abundance of chromium is around 0.00002%. Comparing these values, it is clear that nitrogen is more abundant in the human body than chromium. Answer for (c): Nitrogen (N) is more abundant than chromium (Cr) in the human body.

Key Concepts

Hydrogen: A Key Element in the Human Body

Hydrogen is one of the most essential elements in the human body, accounting for approximately 10% of its mass. It plays several critical roles:

• Hydrogen is a major component of water, which makes up about 60% of the human body. Since our bodies are mostly water, hydrogen's role is fundamental.
• It is also part of organic molecules such as carbohydrates, proteins, and fats, which are crucial for various biological functions.
• Hydrogen ions help in maintaining the body's pH balance, which is necessary for normal cell operations and metabolic processes.

These functions highlight why hydrogen is significantly more abundant than elements like silicon in the human body. Without hydrogen, human life wouldn't be sustainable.
Furthermore, the light nature of hydrogen makes it a key player in reactions and interactions within the body.
This allows hydrogen to actively participate in the creation of energy and other vital processes.

Calcium: Essential for Strong Bones and More

Calcium is a vital element, making up about 1.5% of the human body's mass. Its significant abundance compared to iron shows how crucial it is:

• Calcium is stored mainly in the bones and teeth, providing structural strength and stability. It is what makes the skeleton strong and able to support the body.
• It plays a key role in nerve function, muscle contraction, and blood clotting. These processes are critical for everyday activities like moving and healing from injuries.
• Calcium also acts as a signal molecule for various cellular processes, indicating when certain actions should take place in the body.

This abundance is necessary since the body constantly uses calcium for these vital functions. A deficiency can lead to weakened bones and health issues like osteoporosis.
Having a diet rich in calcium is important for maintaining a healthy body and supporting its functions over time.

Nitrogen: Building Block of Proteins and DNA

Nitrogen constitutes about 2.4% of the human body's mass, highlighting its importance in biological processes. Here's why nitrogen is more abundant than elements like chromium:

• Nitrogen is a fundamental component of amino acids, the building blocks of proteins. Proteins are essential for the growth and repair of body tissues.
• It is also a key element in nucleic acids such as DNA and RNA, which are critical for genetic information storage and transfer.
• Nitrogen aids in the production of hormones and neurotransmitters, which help regulate bodily functions and communication between cells.

The body's reliance on nitrogen for creating proteins and genetic material makes it indispensable for life.
This explains why it is far more prevalent than chromium, as it is involved in nearly every biological process necessary for sustaining life.