Atom with the same atomic number and different mass numbers are called

Options

A. Isobars
B. Isomers
C. Isotones
D. Isotopes

Answer

To solve the question "Atoms with the same atomic number and different mass numbers are called," we can follow these steps:

### Step 1: Understand Atomic Number and Mass Number
- The atomic number of an atom is the number of protons in its nucleus, which defines the element.
- The mass number is the total number of protons and neutrons in the nucleus.

### Step 2: Identify the Relationship
- Atoms that have the same atomic number (same number of protons) but different mass numbers (different total number of protons and neutrons) are variations of the same element.

### Step 3: Define the Term
- These variations are specifically called "isotopes." Isotopes of an element have the same chemical properties because they have the same number of protons and electrons, but they differ in their physical properties due to the difference in mass.

### Step 4: Provide Examples
- For example, carbon has isotopes such as Carbon-12 (6 protons and 6 neutrons) and Carbon-14 (6 protons and 8 neutrons). Both have the same atomic number (6) but different mass numbers (12 and 14).

### Conclusion
- Therefore, the correct answer to the question is that atoms with the same atomic number and different mass numbers are called **isotopes**.

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