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Ch.4 Atoms and Elements
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
All textbooksTimberlake 13th EditionCh.4 Atoms and ElementsProblem 25c
Chapter 4, Problem 25c

Would you use the atomic number, mass number, or both to determine each of the following?
c. number of particles in the nucleus

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1
Understand the composition of the nucleus: The nucleus of an atom contains protons and neutrons. The atomic number represents the number of protons, while the mass number represents the total number of protons and neutrons.
Recall the definition of atomic number: The atomic number is the number of protons in the nucleus of an atom. It is unique to each element and does not include neutrons.
Recall the definition of mass number: The mass number is the sum of the protons and neutrons in the nucleus. It provides the total count of particles in the nucleus.
Determine which value is needed: To find the total number of particles in the nucleus, you need the mass number because it accounts for both protons and neutrons.
Conclude that the atomic number alone is insufficient: While the atomic number gives the number of protons, it does not include neutrons. Therefore, the mass number is required to determine the total number of particles in the nucleus.

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Key Concepts

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

Atomic Number

The atomic number is the number of protons in the nucleus of an atom, which defines the element and its position on the periodic table. It also indicates the number of electrons in a neutral atom, influencing its chemical properties. Understanding the atomic number is essential for identifying the type of element and its behavior in reactions.
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Mass Number

The mass number is the total number of protons and neutrons in an atom's nucleus. It provides insight into the atom's overall mass and stability, as isotopes of an element differ in their neutron count. The mass number is crucial for understanding nuclear properties and the behavior of isotopes in various applications.
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Mass Percent Example

Nucleus Composition

The nucleus of an atom is composed of protons and neutrons, collectively known as nucleons. The number of particles in the nucleus can be determined by the mass number, as it accounts for both protons and neutrons. This concept is fundamental for understanding atomic structure and the forces that hold the nucleus together.
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The Atom (Simplified) Example 1
Related Practice
Textbook Question

Sometimes clothes cling together when removed from a dryer. What kinds of charges are on the clothes?

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Textbook Question

How many protons and electrons are there in a neutral atom of each of the following elements?

a. argon

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Textbook Question

Would you use the atomic number, mass number, or both to determine each of the following?

d. number of electrons in a neutral atom

Textbook Question

On a dry day, your hair flies apart when you brush it. How would you explain this?

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Textbook Question

Is each of the following statements true or false?

c. Neutrons repel each other.

Textbook Question

Write the atomic symbol for the isotope with each of the following characteristics:

c. 25 electrons and 28 neutrons

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