Name FeCl2 and FeCl3 correctly.
Chloride is always -1, so count: two Cl- means iron is +2 → iron(II) chloride; three Cl- means iron is +3 → iron(III) chloride. The fixed charge of chloride is the tool for reading the metal's charge.
What Is the Charge of Chlorine?
Chlorine commonly forms Cl- Cl+ Cl5+ Cl7+ in introductory ionic compounds.
In ionic compounds chlorine is the chloride ion, Cl-, as in NaCl and CaCl2 — assume -1 unless oxygen is involved. In oxyanions chlorine turns positive: +1 in hypochlorite (bleach, ClO-), +5 in chlorate (ClO3-), +7 in perchlorate (ClO4-).
| Element | Chlorine |
|---|---|
| Symbol | Cl |
| Atomic number | 17 |
| Common ionic charge | -1, +1, +5, +7 |
| Common ions | Cl-, Cl+, Cl5+, Cl7+ |
Visual reference
Chlorine element image and atomic model
Images are used as visual references; charge rules still depend on the compound.
Why Chlorine pulls one electron in
Chlorine is [Ne]3s2 3p5, one electron from argon's configuration, and highly electronegative (3.16) — so it takes one electron from nearly everything. Only oxygen and fluorine pull harder; against them, chlorine's seven valence electrons can all be pushed into the shared column, allowing states up to +7.
The Chlorine mix-up to watch for
Reading 'chlorine' and 'chloride' as synonyms. Chlorine (Cl2) is a toxic yellow-green gas; chloride (Cl-) is half of table salt. On formula problems, the '-ide' ending is your signal to write the -1 ion.
Worked example: Cl in a formula problem
Cl- and Cl+ and Cl5+ and Cl7+ in real compounds
NaCl
sodium chlorine compound
Sodium ions can balance Cl- in simple ionic examples.
CaCl2
calcium chlorine compound
Calcium ions can balance common negative Chlorine ions.
Questions students ask about chlorine
What is the charge of chlorine in bleach?
+1. Household bleach is sodium hypochlorite, NaOCl: with Na at +1 and O at -2, chlorine must be +1. Its eagerness to fall back to -1 is precisely what destroys stains and germs.
Is the chlorine in swimming pools Cl- ions?
The disinfecting species is hypochlorous acid (HOCl, chlorine +1), not chloride. Chloride is what remains after the sanitizer has done its work — harmless and tasteless at pool levels.
Why does perchlorate show up in rocket fuel?
In ClO4-, chlorine sits at +7, its most electron-poor state. Falling from +7 back to -1 releases a torrent of energy — ammonium perchlorate provides exactly that in solid rocket boosters.
How do I use this charge in formulas?
Combine positive and negative ions so the total charge is zero — or let the ionic compound calculator do the crossing for you. The full chart lives on the periodic table with charges.
Where this data comes from
Charges and element facts on this page are checked against the primary references below. Found an error? Email hello@periodictablewithcharges.com — corrections ship in the next content update. See how this site is edited.