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Ch.2 - Atoms, Molecules & Ions
Chapter 2, Problem 47

Which element accounts for roughly 75% of the observed mass of the universe? Which four elements make up 95% of the mass of the human body?

Verified step by step guidance
1
Step 1: Identify the element that is most abundant in the universe. Hydrogen is the simplest and most abundant element, making up roughly 75% of the universe's mass.
Step 2: Consider the composition of the human body, which is primarily made up of a few key elements.
Step 3: Recognize that the four elements that make up 95% of the human body's mass are oxygen, carbon, hydrogen, and nitrogen.
Step 4: Understand that these elements are essential for the formation of water, organic molecules, and proteins, which are crucial for life.
Step 5: Summarize that hydrogen is the most abundant element in the universe, while oxygen, carbon, hydrogen, and nitrogen are the primary elements in the human body.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Abundance of Elements in the Universe

Hydrogen is the most abundant element in the universe, accounting for about 75% of its observed mass. This predominance is due to hydrogen's simple structure and its role in the formation of stars and galaxies. Understanding the distribution of elements helps in studying cosmic evolution and the formation of matter.
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Composition of the Human Body

The human body is primarily composed of four elements: oxygen, carbon, hydrogen, and nitrogen, which together make up approximately 95% of its mass. Oxygen is crucial for respiration, carbon forms the backbone of organic molecules, hydrogen is involved in water and organic compounds, and nitrogen is essential for amino acids and nucleic acids.
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Elemental Abundance and Life

The elemental abundance in both the universe and living organisms highlights the connection between cosmic processes and biological systems. The elements that dominate the universe are also fundamental to life on Earth, illustrating how the conditions of the early universe influenced the development of life and the biochemical processes that sustain it.
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