How do you decide ionic vs covalent?

If a metal or polyatomic cation pairs with a nonmetal or polyatomic anion, the compound is usually ionic. Nonmetal plus nonmetal compounds usually use covalent prefix naming.

When do I use Roman numerals in chemical names?

Use Roman numerals for variable-charge metals such as iron, copper, tin, lead, chromium, and manganese. The numeral shows the metal ion charge determined by charge balance.

Does this calculator support hydrates and acids?

Yes. It supports common binary acids, oxoacids, and hydrates such as copper(II) sulfate pentahydrate, using general-chemistry naming patterns.

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Chemical Name ⇄ Formula Calculator

Q: Why might a chemical naming result be marked Check?

Some names are ambiguous without oxidation state, structure, or course-specific naming rules. For transition metals, add the Roman numeral when known and verify ambiguous results with your course materials.

Convert between a chemical name and its formula. Supports common ionic, covalent, acid, hydrate, and polyatomic ion naming patterns, with result confidence and step-by-step logic.

Background

Naming depends on compound class. Ionic names use cation + anion and Roman numerals for variable-charge metals. Covalent names use Greek prefixes. Acids and hydrates follow their own naming patterns, so the calculator now shows how it classified the input instead of only returning an answer.

Enter a name or formula

Name or formula

Tip: Add Roman numerals for transition metals when known, for example copper(II) sulfate instead of just copper sulfate.

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Step-by-step reasoning

Element count chart and table

Quick picks (click to see result):

Result

No results yet. Enter a name or formula and click Convert.

How to use this calculator

Input: Type either a chemical name or a formula. The calculator detects direction automatically.
Use Roman numerals: For variable-charge metals, use names like iron(III), copper(II), or tin(IV).
Review confidence: If the calculator marks an answer as “Check,” verify it against your class rules.

Formula & Equation Used

Ionic: cation + anion; subscripts balance total positive and negative charge.

Covalent: Greek prefixes give atom counts, with no mono- on the first element.

Acids: binary acids use hydro-...-ic acid; oxoacids follow ate → ic and ite → ous.

Hydrates: a water count after the dot becomes mono-, di-, tri-, penta-hydrate, etc.

Frequently Asked Questions

Q: Why might a chemical naming result be marked “Check”?

Some compounds are ambiguous without oxidation state, structure, or course-specific naming rules. Transition metals are the most common case.

Q: What was improved in this version?

The calculator now better handles ammonium/polyatomic formulas, oxide prefix contractions like monoxide, common compounds like glucose, and gives clearer confidence notes.

Polyatomic Ions