Problem 1 - Biology: The Unity and Diversity of Life

Question

What atom has only one proton? a. hydrogen b. an isotope c. a free radical d. a radioisotope

Step-by-Step Solution

Answer

The atom with only one proton is a hydrogen atom.

Step 1: Understanding Atomic Structure

Atoms are composed of protons, neutrons, and electrons. The number of protons in an atom's nucleus defines the element's atomic number, which determines the identity of the element.

Step 2: Identifying the Element

The atomic number of hydrogen is 1, meaning it has exactly one proton in its nucleus. This unique property of having one proton distinguishes hydrogen from all other elements.

Step 3: Analyzing the Options

Option a. hydrogen correctly indicates the element with only one proton. Option b. an isotope refers to atoms with the same number of protons but a different number of neutrons. Option c. a free radical refers to an atom, molecule, or ion with unpaired valence electrons. Option d. a radioisotope is an isotope that is radioactive.

Step 4: Conclusion

Hydrogen is the element with only one proton, as no other options uniquely define such an atom. Therefore, option a. hydrogen is the correct answer.

Key Concepts

Hydrogen Atom

A hydrogen atom is the simplest and most abundant element in the universe. It consists of just one proton and one electron. This simplicity makes hydrogen unique, as it lacks neutrons in its most common form. In scientific notation, hydrogen is represented by the symbol H and carries an atomic number of 1. This singular proton in the nucleus is what gives hydrogen its identity among all elements on the periodic table.

Hydrogen plays a crucial role in chemistry and biology. It is a key component in water, organic compounds, and is essential for life. Understanding hydrogen is essential for anyone studying chemistry, as its properties and interactions form the foundation of many chemical reactions. It is also interesting to note that despite its simplicity, hydrogen has significant isotopic variations which we’ll explore further.

Protons

Protons are positively charged particles found in the nucleus of an atom. Alongside neutrons, they form the core of the atom, held together by the strong nuclear force. The number of protons in the nucleus of an atom is what defines its identity, also known as the atomic number.

For example:

• Hydrogen, with one proton, has an atomic number of 1.
• Helium has two protons, making its atomic number 2.

The presence and number of protons determine the element's place on the periodic table. Protons are critical to binding electrons around the nucleus, balancing the atom’s charge and affecting chemical properties. Their number is usually equal to the number of electrons, resulting in a neutral atom. The understanding of protons is foundational for comprehending how elements differ from each other and how chemical reactions occur.

Isotopes

Isotopes are variations of a particular element that have the same number of protons, but different numbers of neutrons in the nucleus. This means that while isotopes of the same element possess the same atomic number, they have different mass numbers due to the varying number of neutrons.

For instance, hydrogen has three main isotopes:

• Protium, with no neutrons
• Deuterium, with one neutron
• Tritium, with two neutrons

These differing nuclear compositions can lead to varying stability and radioactive properties. Isotopes are key in various scientific applications, such as radiometric dating, medical diagnostics, and nuclear power generation. However, all isotopes of an element share the same chemical behavior because chemical properties are determined by electron configurations, which are not affected by the number of neutrons.

Element Identification

Element identification involves determining the element based on the number of protons in its nucleus. Known as the atomic number, this unique number is fundamental to the periodic table, allowing scientists to categorize and distinguish each element from others.

For hydrogen, this identification is straightforward—the atomic number is 1, so it only has one proton. Identifying elements through atomic numbers is crucial for scientists, as it creates a systematic way to understand chemical behavior and predict how different elements will react with each other.

Moreover, this identification method helps scientists in distinguishing isotopes from different elements. This structural understanding assists in nuclear chemistry, physics, and various industrial applications, making element identification a core part of scientific inquiry and education. Through element identification, we unlock the periodic table, understanding the building blocks of everything around us.