For which of the following reasons does a chloride ion have a negative charge?
A.
It gained an electron.
B.
It lost an electron.
C.
It lost a proton.
D.
It gained a proton.
The Correct Answer and Explanation is :
The correct answer is:
A. It gained an electron.
Explanation:
Chloride ions (Cl⁻) are negatively charged ions formed from chlorine atoms. To understand why chloride ions have a negative charge, it’s important to examine the basic concepts of atomic structure and ion formation.
1. Atomic Structure and Charge: An atom is composed of three main subatomic particles: protons, neutrons, and electrons. Protons have a positive charge, electrons have a negative charge, and neutrons are neutral. In a neutral atom, the number of protons equals the number of electrons, which balances out the charges and results in no overall charge.
2. Formation of Ions: When an atom gains or loses electrons, it becomes an ion. If an atom gains electrons, it has more negatively charged electrons than positively charged protons, resulting in a negative charge. Conversely, if an atom loses electrons, it has more protons than electrons, leading to a positive charge.
3. Chlorine Atom and Ion Formation: Chlorine (Cl) is an element with an atomic number of 17, meaning it has 17 protons and, in its neutral state, 17 electrons. The electronic configuration of chlorine is 2-8-7, where it has seven electrons in its outermost shell (valence shell).
4. Chlorine’s Tendency to Gain an Electron: Chlorine atoms are highly reactive and have a strong tendency to gain one electron to complete their valence shell, achieving a stable electronic configuration similar to that of noble gases. By gaining an electron, chlorine’s electronic configuration becomes 2-8-8. This extra electron gives the chlorine atom a negative charge because the number of electrons (18) now exceeds the number of protons (17), resulting in a Cl⁻ ion.
5. Charge of Chloride Ion: Thus, when a chlorine atom gains an electron, it becomes a chloride ion (Cl⁻), with an overall negative charge of -1 due to the additional electron.
In summary, a chloride ion has a negative charge because it has gained an electron, which adds an extra negative charge to the atom. This gain of an electron is crucial for chlorine to achieve a stable electron configuration.