an ion which has 18 electrons in the outermost shell is
An ion which has 18 electrons in the outermost shell is
Answer: To determine which ion has 18 electrons in its outermost shell, we need to analyze the electronic configuration of various ions and identify one that corresponds to this condition.
Solution By Steps:
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Understanding Electronic Configuration:
- In general, ions are formed when atoms gain or lose electrons to achieve a stable electronic configuration, often resembling the nearest noble gas.
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Noble Gas Reference:
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The noble gas with 18 electrons in its shell structure is Argon (Ar), which has the electronic configuration:
1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6 -
This configuration indicates a complete and stable set of electron shells.
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Identify the Ion:
- For an ion to have 18 electrons in its outermost shell (which is actually the third shell for Argon), we can consider ions that would achieve this by gaining or losing electrons.
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Common Ions:
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Sulfide Ion (S$^{2-}$):
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Sulfur (S) has an atomic number of 16, so its neutral atom electronic configuration is:
1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^4 -
By gaining 2 electrons to form S$^{2-}$, it achieves the configuration:
1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6 -
This results in a total of 18 electrons, with the outermost shell being fully occupied by 18 electrons.
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Chloride Ion (Cl$^{-}$):
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Chlorine (Cl) has an atomic number of 17, so its neutral atom electronic configuration is:
1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^5 -
By gaining 1 electron to form Cl$^{-}$, it achieves the configuration:
$$$
1s^2, 2s^2, 2p^6, 3s^2, 3p^6- This also results in a total of 18 electrons, fully occupying the outer shell. ### Common Ions with 18 Electrons: Several ions can have 18 electrons: 1. **Sulfide Ion (S$^{2-}$)**: - Configuration: $1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6$ 2. **Chloride Ion (Cl$^{-}$)**: - Configuration: $1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6$ 3. **Potassium Ion (K$^+$)**: - Potassium’s neutral configuration is $1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6\, 4s^1$. - Losing one electron to form K$^+$ results in $1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6$ ### Final Answer: An ion which has 18 electrons in the outermost shell can commonly be the **Sulfide Ion (S$^{2-}$)**, **Chloride Ion (Cl$^{-}$)**, or **Potassium Ion (K$^+$)**. These ions achieve a stable electronic configuration similar to that of the noble gas Argon, with 18 electrons in the outermost shell.
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