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Ch.2 - Atoms, Molecules, and Ions
Chapter 2, Problem 27e,f

How many protons, neutrons, and electrons are in the following atoms? (e) 184W (f) 181Ta.

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Identify the atomic number of tungsten (W) from the periodic table, which is 74. This number represents the number of protons in the atom.
Since the atom is neutral, the number of electrons is equal to the number of protons. Therefore, tungsten has 74 electrons.
The mass number of the tungsten isotope is given as 184. The mass number is the sum of protons and neutrons in the nucleus.
To find the number of neutrons, subtract the atomic number (number of protons) from the mass number: Neutrons = Mass number - Atomic number = 184 - 74.
Summarize the findings: Tungsten (W) with a mass number of 184 has 74 protons, 74 electrons, and the calculated number of neutrons.

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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 three primary subatomic particles: protons, neutrons, and electrons. Protons are positively charged and reside in the nucleus, while neutrons are neutral particles also found in the nucleus. Electrons are negatively charged and orbit the nucleus in electron shells. The number of protons defines the element, while the total number of protons and neutrons gives the atomic mass.
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Guided course
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Atom Structure

Atomic Number and Mass Number

The atomic number of an element is the number of protons in its nucleus, which determines the element's identity. The mass number is the sum of protons and neutrons in the nucleus. For the isotope notation (e.g., 184W), 'W' represents tungsten, and '184' indicates the mass number, allowing us to deduce the number of neutrons by subtracting the atomic number from the mass number.
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Isotopes

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons. This results in different mass numbers for the isotopes of the same element. Understanding isotopes is crucial for determining the composition of an atom, as it affects its stability and behavior in chemical reactions.
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