To determine the stability of an atom, we need to consider its electron configuration, particularly in the outermost shell, also known as the valence shell. Here's a step-by-step explanation:
1. Understanding Atomic Structure:
- Atoms consist of protons, neutrons, and electrons.
- Protons and neutrons are in the nucleus, while electrons orbit the nucleus in different energy levels or shells.
2. Electron Configuration:
- Electrons fill the energy levels or shells around the nucleus starting from the innermost shell.
- Each shell has a maximum number of electrons it can hold. For instance, the first shell can hold up to 2 electrons, the second shell up to 8 electrons, and so on.
3. Most Stable State:
- Atoms strive to reach a stable state, which commonly involves having a full valence shell. This minimizes the energy and makes the atom less reactive.
- For most elements, this means having 8 electrons in their outermost shell (this is known as the octet rule), except for the first shell, which is complete with 2 electrons.
4. Evaluating the Options:
- Option 1: All of the electron positions in the outermost shell are filled.
- This aligns with our understanding that a full valence shell represents a stable electron configuration.
- Option 2: The number of neutrons = number of protons.
- While this might indicate some balance, it does not directly impact the chemical stability of the atom regarding its electrons.
- Option 3: When all of the proton positions in the outermost shell are filled.
- There are no specific "proton positions" in the outermost shell that need to be filled. Protons reside in the nucleus and are not configured in shells like electrons.
- Option 4: When the number of electrons = number of protons.
- This indicates a neutral charge state, not necessarily the most stable electron configuration.
5. Conclusion:
- The stability of an atom in terms of its electron configuration is achieved when the outermost shell is fully occupied by electrons.
Therefore, the most accurate statement is:
"All of the electron positions in the outermost shell are filled."
