When iron forms the ionic compound FeCl_3, how many electrons does the iron ion have?

• A. 23
• B. 26
• C. 24
• D. 28

Answer: (C)

Verified step by step guidance

1. Identify the atomic number of iron (Fe), which tells you the number of protons and, in a neutral atom, also the number of electrons. Iron has an atomic number of 26, so a neutral Fe atom has 26 electrons.
2. Determine the charge on the iron ion in FeCl_3. Since each chloride ion (Cl^-) has a charge of -1 and there are three chloride ions, the total negative charge is -3. To balance this, the iron ion must have a charge of +3, making it Fe^{3+}.
3. Understand that when iron forms a Fe^{3+} ion, it loses 3 electrons compared to the neutral atom. This is because the positive charge indicates a loss of electrons.
4. Calculate the number of electrons in the Fe^{3+} ion by subtracting 3 electrons from the neutral iron atom's 26 electrons: 26 - 3 = 23 electrons.
5. Conclude that the Fe^{3+} ion in FeCl_3 has 23 electrons.