To determine the correct atomic number of the anion, let's carefully analyze the given information and the nature of an anion.
1. Definition of an Anion: An anion is a negatively charged ion. This negative charge arises because an anion has more electrons than protons.
2. Given Information:
- Number of electrons = 4
- Number of neutrons = 5
3. To determine the atomic number, we need to find the number of protons in the nucleus of this anion.
- Characteristic of an Anion: Since an anion has more electrons than protons, the anion in question has more electrons (4) than protons.
4. Deduction:
- The atomic number represents the number of protons.
- Therefore, the number of protons in this anion must be one less than the number of electrons to maintain the negative charge characteristic of an anion.
5. Calculation Summary:
- Electrons = 4,
- Anion implies protons < electrons.
- Therefore, protons = 4 - 1 = 3.
6. Conclusion: The atomic number, which indicates the number of protons in the nucleus, is 3.
Thus, the correct answer is:
a) less than 4 since an anion should have less protons than electrons.
