Determine the electron arrangement for the Cl^– ion.

• A. 2-8-7
• B. 2-8-8
• C. 2-8-6
• D. 2-2-6-2-6
• E. 2-2-6-2-5

Answer: (B)

Verified step by step guidance

1. Understand that the Cl– ion is a chloride ion, which means it has gained an extra electron compared to a neutral chlorine atom.
2. Recall that a neutral chlorine atom has an atomic number of 17, indicating it has 17 electrons. The electron configuration for a neutral chlorine atom is 2-8-7.
3. Since the Cl– ion has gained one additional electron, it now has 18 electrons instead of 17.
4. Distribute these 18 electrons according to the electron shell model: the first shell can hold up to 2 electrons, the second shell can hold up to 8 electrons, and the third shell can hold up to 8 electrons.
5. Arrange the electrons in the shells: 2 electrons in the first shell, 8 electrons in the second shell, and 8 electrons in the third shell, resulting in the electron configuration of 2-8-8 for the Cl– ion.