---
title: "Iron(II) Chloride | Intro to Chemistry"
description: "Iron(II) chloride, FeCl2, is a green, soluble transition-metal salt with Fe2+ ions, used to show oxidation states, ionic bonding, and redox prep in Intro to Chemistry."
canonical: "https://fiveable.me/intro-chem/key-terms/ironii-chloride"
type: "key-term"
subject: "Intro to Chemistry"
unit: "Unit 19"
---

# Iron(II) Chloride | Intro to Chemistry

## Definition

Iron(II) chloride is the ionic compound FeCl2, made of Fe2+ and Cl- ions. In Intro to Chemistry, it shows how transition metals form compounds with specific oxidation states and how those compounds behave in water.

## What It Is

Iron(II) chloride is the compound FeCl2, which means each formula unit contains one iron ion in the +2 oxidation state and two chloride ions. In Intro to Chemistry, you usually meet it as an example of a transition-metal salt, not just as a memorized formula. The name tells you the iron is Fe2+, and that oxidation state matters because iron can form more than one stable ion.

It is often called ferrous chloride, which is the older naming style for iron(II). Both names point to the same substance, but the Stock name, iron(II) chloride, is the one that makes the charge clearer. That charge is part of the chemistry: Fe2+ balances with two Cl- ions to make a neutral ionic compound.

Iron(II) chloride is typically described as a green crystalline solid and it dissolves in water. That makes sense in an Intro to Chemistry unit on ionic compounds, because many metal chlorides separate into ions when placed in polar solvents like water. Once dissolved, the compound no longer behaves like a pile of crystals. It behaves as hydrated ions moving through solution.

A useful way to think about it is as a product of both formation and composition. One common preparation is reacting iron metal with hydrochloric acid, which produces FeCl2 and hydrogen gas. Another route is reducing iron(III) chloride to iron(II) chloride, which shows how redox chemistry can move iron between oxidation states.

This compound also shows up in transition-metal chemistry because iron has partially filled d orbitals in its common ions. That is why iron(II) chloride is paramagnetic, meaning the Fe2+ ion has unpaired electrons. In a basic chemistry course, that property connects electron configuration to magnetism, which is one of the cleaner examples of how transition metals differ from many main-group ions.

## Why It Matters

Iron(II) chloride matters because it is a clean example of several Intro to Chemistry ideas all at once: naming ionic compounds, tracking oxidation states, predicting solubility, and recognizing redox reactions. If you can make sense of FeCl2, you are using the same skills that show up across much of a first chemistry course.

It is especially useful when you are learning that transition metals can have more than one charge. Iron does not always form the same ion, so the Roman numeral in iron(II) chloride is not decoration. It tells you which ion is present and prevents confusion with iron(III) compounds, which behave differently in reactions and solutions.

The compound also gives you a concrete example of how preparation and properties connect. If iron metal reacts with hydrochloric acid, you can trace which substance is oxidized, which is reduced, and why hydrogen gas appears. That kind of before-and-after thinking is exactly what chemistry problems ask you to do.

Because FeCl2 is soluble, it can be discussed in solution chemistry, lab observations, and ion-based equations. Because it contains a transition metal, it can also lead into electron configuration and magnetic behavior. So this one compound acts like a bridge between naming, structure, reactivity, and properties.

## Connections

### Transition Metals

Iron is a transition metal, so iron(II) chloride is not just another simple salt. Its chemistry reflects the fact that transition metals can form more than one ion, and that flexibility is why the Roman numeral matters. The compound is a straightforward way to see how d-block elements differ from many main-group metals.

### Oxidation State

The II in iron(II) chloride tells you the oxidation state of iron is +2. That number is central for naming the compound, writing formulas, and following redox reactions. If iron changes from +2 to +3, you are no longer talking about the same compound, so oxidation state changes the chemistry you predict.

### Coordination Compound

Iron(II) chloride can be a starting point for coordination chemistry because Fe2+ can bind ligands in solution. Even when the compound itself is just a simple salt, the dissolved iron ion can form complexes with water or other ligands. That makes it a good bridge into the idea that transition metals often exist as coordinated ions, not just isolated atoms.

### [Copper(II) Sulfate](/intro-chem/key-terms/copperii-sulfate)

Copper(II) sulfate is a helpful comparison because it is another named transition-metal salt with a Roman numeral. Comparing it with iron(II) chloride helps you focus on two ideas at once: the metal ion charge and the anion present. Both compounds are examples of how transition-metal naming works in a basic chemistry class.

## On the AP Exam

A quiz question might ask you to write the formula from the name, identify the oxidation state of iron, or predict whether the compound is ionic and soluble in water. On a lab quiz, you could be given a green solution or a reaction product and asked whether iron(II) chloride could be present based on color, solubility, or the reaction conditions. If the class covers redox, you may also need to trace how Fe2+ is formed from iron metal or from iron(III) chloride.

When you see FeCl2 on a problem set, the move is to name the ions, check charge balance, and connect that to the compound's behavior in solution. That same logic also shows up when you compare it with other iron salts or explain why the Roman numeral matters in transition-metal naming.

## Iron(II) Chloride vs Iron(III) chloride

Iron(II) chloride contains Fe2+, while iron(III) chloride contains Fe3+. They are different compounds with different formulas, names, and chemistry, so the Roman numeral changes both the identity and the charge balance. If you mix them up, you will write the wrong formula and probably predict the wrong reaction behavior.

## Key Takeaways

- Iron(II) chloride is FeCl2, an ionic compound made from Fe2+ and Cl- ions.
- The Roman numeral II tells you the iron oxidation state is +2, which matters in naming and redox chemistry.
- It is a transition-metal salt, so it connects to electron configuration, variable charges, and paramagnetism.
- It is soluble in water, so in solution it separates into ions rather than staying as a crystal.
- You often use it as an example of how iron can be made from acid-metal reactions or reduced from iron(III) compounds.

## FAQs

### What is iron(II) chloride in Intro to Chemistry?

Iron(II) chloride is the ionic compound FeCl2. It contains iron in the +2 oxidation state and two chloride ions to balance the charge. In Intro to Chemistry, it shows how transition-metal compounds are named and how their formulas reflect ion charges.

### Is iron(II) chloride the same as ferrous chloride?

Yes. Ferrous chloride is the older name for iron(II) chloride. The modern Stock name is usually easier to read because the Roman numeral tells you the iron charge directly.

### How is iron(II) chloride prepared?

A common preparation is reacting iron metal with hydrochloric acid, which produces iron(II) chloride and hydrogen gas. It can also be made by reducing iron(III) chloride. Both routes show up in Intro to Chemistry as examples of redox and compound formation.

### Why is iron(II) chloride paramagnetic?

Iron(II) chloride is paramagnetic because the Fe2+ ion has unpaired electrons in its d orbitals. That links the compound to electron configuration and transition-metal behavior, not just to simple ionic naming.

## Related Study Guides

- [19.1 Occurrence, Preparation, and Properties of Transition Metals and Their Compounds](/intro-chem/unit-19/1-occurrence-preparation-properties-transition-metals-compounds/study-guide/tfIsOMJmKaGORifZ)

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