Textbook Question
State the number of electrons lost or gained when the following elements form ions:
e. Rb
2. Atoms and the Periodic Table
Ions and the Octet Rule (Simplified)
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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
Verified step by step guidance1
Understand that the Cl– ion is a chloride ion, which means it has gained an extra electron compared to a neutral chlorine atom.
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.
Since the Cl– ion has gained one additional electron, it now has 18 electrons instead of 17.
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.
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.
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