Ions & Charges Chart
The ultimate reference for Polyatomic Ions, Cations, and Anions. Master chemical nomenclature, learn the "-ate vs -ite" rules, and understand electrolytes.
The Language of Chemistry
Learning ions is like learning the alphabet of chemistry. You can't write sentences (chemical formulas) without knowing your letters (cations and anions).
An Ion is simply an atom that has gained or lost weight (electrons). If it loses negatively charged electrons, it becomes positive (Cation). If it gains them, it becomes negative (Anion).
Cracking the Code: -ate vs -ite
Polyatomic ions often come in families. The difference is usually just the number of Oxygen atoms.
"I ate too much oxygen."
"It's a lite version."
Monoatomic vs Polyatomic
Monoatomic Ions are simple single atoms that have charged up (e.g., Na⁺, Cl⁻).
Polyatomic Ions are essentially "charged molecules". They are gangs of atoms held together by strong covalent bonds that act as a single unit. You cannot break them apart in normal reactions. When you need two Nitrates, you write (NO₃)₂, never N₂O₆!
Memory Cheat Sheet
- Silver (Ag) is always +1, even though it's a transition metal.
- Zinc (Zn) and Cadmium (Cd) are always +2.
- Hydroxide (OH⁻) and Cyanide (CN⁻) are the weird -ides that are polyatomic.
The "Big 5" to Memorize
Frequently Asked Questions
What is the "Big 5" rule for polyatomic ions?
The "Big 5" are the most common -ate ions: Nitrate (NO₃⁻), Chlorate (ClO₃⁻), Carbonate (CO₃²⁻), Sulfate (SO₄²⁻), and Phosphate (PO₄³⁻). Memorizing these helps you derive others like -ites and per-ates.
What is the difference between -ate and -ite?
The suffix -ate indicates the standard number of oxygen atoms (e.g., Nitrate NO₃⁻). The suffix -ite indicates one less oxygen atom but the same charge (e.g., Nitrite NO₂⁻).
Why is Ammonium unique?
Ammonium (NH₄⁺) is one of the few common positively charged polyatomic ions (cations). Most polyatomic ions are negatively charged (anions).
How do I know the charge of a transition metal?
Transition metals like Iron and Copper have variable charges. You must look at the Roman numeral in the name (Iron(II) = +2) or deduce it from the anion it is bonded to in a formula.
What is an electrolyte?
Electrolytes are substances that produce ions when dissolved in water, allowing the solution to conduct electricity. Common examples are Sodium (Na⁺), Potassium (K⁺), and Chloride (Cl⁻).
What are the diatomic elements?
The "BrINClHOF" elements (Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, Fluorine) exist as pairs (e.g., O₂) when pure. However, as ions, they exist as charged single atoms (e.g., Oxide O²⁻) or parts of groups.
Does Hydrogen form a cation or anion?
Uniquely, Hydrogen can form both! It usually forms a cation (H⁺, proton) in acids, but can form an anion (H⁻, hydride) when bonded to metals.
Why do elements lose or gain electrons?
Atoms lose or gain electrons to achieve a stable "octet"—a full outer shell of 8 valence electrons, similar to a Noble Gas configuration.
How do you write formulas with polyatomic ions?
Treat the polyatomic ion as a single unit. If you need more than one, use parentheses. Example: Magnesium Nitrate is Mg(NO₃)₂, because Mg is +2 and Nitrate is -1.
What is the charge of Zinc and Silver?
Although they are transition metals, Zinc almost always forms Zn²⁺ and Silver almost always forms Ag⁺. They are effectively fixed-charge metals.