How many electrons will chlorine gain or lose when it forma an ion?
A) lose 1
B) gain 1
C) lose 7
Dj gain 2 B) lose 3
The correct answer and explanation is :
The correct answer is B) gain 1.
Explanation:
Chlorine is a halogen, with the atomic number 17. This means that a neutral chlorine atom has 17 electrons, and the electron configuration of chlorine is:
$\text{Cl}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^5$
This means chlorine has 7 electrons in its outermost (third) energy level (3s^2 3p^5), which is one electron short of having a full octet of 8 electrons in that outermost shell. For chlorine to achieve the stable electron configuration of a noble gas (like argon), it needs to gain one electron.
When chlorine gains this electron, it becomes a negatively charged ion, called a chloride ion ($Cl^-$). The addition of this extra electron gives chlorine a total of 18 electrons (which is the same number as the noble gas argon), making it stable. The chloride ion has a charge of -1, indicating that it has one more electron than protons.
Why chlorine gains an electron:
- Electron configuration: Chlorine has 7 electrons in its outer shell and needs 1 more to complete its octet (8 electrons).
- Stability: By gaining an electron, chlorine achieves a full outer shell, making it more stable and energetically favorable.
- Ion formation: Since gaining an electron gives chlorine a negative charge, it becomes a chloride ion ($Cl^-$) with a charge of -1.
Why chlorine does not lose electrons:
- Losing electrons would result in a positive charge. However, for chlorine to achieve stability, it would need to lose 7 electrons, which would leave it with just 10 electrons, making it highly unstable. Therefore, losing electrons is not energetically favorable for chlorine.
Thus, chlorine will gain 1 electron to form a chloride ion, making option B the correct answer.