Isotopes are defined as atoms of the same element that possess:

Question

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The correct answer is Option B: The same atomic number but different mass numbers. Isotopes are variants of a particular chemical element that have the same number of protons (atomic number) but a different number of neutrons, leading to different mass numbers. Because they have the same atomic number, they occupy the same position in the periodic table and share nearly identical chemical properties.

Step-by-Step Solution & Concepts:
Isotopes are variants of a particular chemical element that have the same number of protons (atomic number) but a different number of neutrons, leading to different mass numbers. Because they have the same atomic number, they occupy the same position in the periodic table and share nearly identical chemical properties.

Working Principle: The atomic number ($Z$) is defined by the number of protons in the nucleus, which dictates the electronic structure and chemical behavior. The mass number ($A$) is defined by the sum of protons ($Z$) and neutrons ($N$), expressed as $A = Z + N$. Since $Z$ is fixed for an element, variations in $N$ directly result in different mass numbers $A$.

Key Formulas: $A = Z + N$ — where $A$ is mass number, $Z$ is atomic number (protons), and $N$ is neutron number.

Key Points: Isotopes of an element have the same number of electrons and protons.; Isotopes have different physical properties (e.g., density, rate of diffusion) due to differing mass.; Chemical properties remain almost identical because they depend on valence electrons.

Advantages: Used in medical diagnostics (radioisotopes).; Essential for carbon dating organic materials.

Disadvantages: Some isotopes are radioactive and can be unstable, requiring careful handling.

Applications: Carbon-14 dating for archaeological findings.; Cobalt-60 in cancer radiotherapy.

Additional Info: Hydrogen has three natural isotopes: Protium ($^1H$), Deuterium ($^2H$), and Tritium ($^3H$).. Option A is incorrect because same neutrons and different atomic numbers define isotones.. Option C is incorrect because same mass number and different atomic numbers define isobars.

Answer: B is correct — Isotopes are atoms of the same element characterized by identical atomic numbers but differing mass numbers due to variations in the number of neutrons.

Exam Tip: Always remember: 'Isobar' ends in 'r' for 'Related mass', 'Isotope' ends in 'p' for 'Proton count', and 'Isotone' ends in 'n' for 'Neutron count'.

Examoogle · Answer

Option A: The same number of neutrons but different atomic numbers

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Option C: The same mass number but different atomic numbers

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Option D: Different electronic configurations but the same atomic mass

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