Atomic umber (z) is equal to

Options

A. number protons in the nucleus of an atom
B. number of electrons in a neutral atom
C. Both (1) and (2)
D. None of the above

Answer

### Step-by-Step Solution:

1. **Understanding Atomic Number (Z)**:
- The atomic number (Z) of an element is defined as the number of protons present in the nucleus of an atom.

2. **Relation to Electrons**:
- In a neutral atom, the number of protons is equal to the number of electrons. Therefore, the atomic number is also equal to the number of electrons in a neutral atom.

3. **Charged Atoms**:
- If an atom is ionized (charged), it may have lost or gained electrons. In this case, the number of electrons will not equal the atomic number. For example, if an atom loses an electron, it becomes positively charged, and if it gains an electron, it becomes negatively charged.

4. **Conclusion**:
- Therefore, the atomic number (Z) is equal to:
- The number of protons in the nucleus of an atom.
- The number of electrons in a neutral atom.

5. **Final Answer**:
- The atomic number (Z) is equal to the number of protons and, in a neutral atom, also equal to the number of electrons.