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Ch.2 - Atoms, Molecules & Ions
Chapter 2, Problem 105a

How many protons and neutrons are in the nucleus of the following atoms? (a)

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1
Step 1: Identify the atomic number and mass number of the atom. The atomic number is the number of protons in an atom, and it is unique for each element. The mass number is the total number of protons and neutrons in an atom.
Step 2: To find the number of protons, simply look at the atomic number of the atom. This number is usually located at the bottom left of the element symbol in the periodic table.
Step 3: To find the number of neutrons, subtract the atomic number from the mass number. This is because the mass number is the sum of protons and neutrons, so subtracting the number of protons (the atomic number) will give you the number of neutrons.
Step 4: If the atom is neutral, the number of electrons will be equal to the number of protons. If the atom is an ion, the number of electrons will be different from the number of protons.
Step 5: Remember that the number of protons defines the element. Changing the number of neutrons results in isotopes, and changing the number of electrons results in ions.

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Key Concepts

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

Atomic Structure

Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in orbitals. The number of protons defines the element and is known as the atomic number, while the total number of protons and neutrons gives the atomic mass number. Understanding atomic structure is essential for determining the composition of different elements.
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Atom Structure

Protons and Neutrons

Protons are positively charged particles found in the nucleus, and their number determines the identity of the element. Neutrons are neutral particles that contribute to the atomic mass but do not affect the charge. The balance of protons and neutrons influences the stability of the nucleus and the isotopes of an element.
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Neutron-to-Proton Plot

Isotopes

Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This difference in neutron count results in varying atomic mass numbers. Understanding isotopes is crucial for applications in nuclear chemistry, radiometric dating, and medical imaging.
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