Counting Elements and Atoms Calculator

Counting Elements and Atoms Calculator

Enter a chemical formula (e.g., H2O, CO2, C6H12O6):

Here’s a table summarizing how to count elements and atoms in a chemical formula:


Counting Elements and Atoms in a Chemical Formula

TermDefinitionExampleElements PresentTotal Atoms
ElementA pure substance consisting of only one type of atom.O (Oxygen)Oxygen1
MoleculeTwo or more atoms chemically bonded together.O₂ (Oxygen Gas)Oxygen2
CompoundA substance composed of two or more different elements.H₂O (Water)Hydrogen (H), Oxygen (O)3
SubscriptThe small number written after an element symbol, indicating the number of atoms of that element.CO₂ (Carbon Dioxide)Carbon (C), Oxygen (O)3 (1C, 2O)
CoefficientA number before a formula indicating how many molecules or formula units are present.2H₂O (Water)Hydrogen (H), Oxygen (O)6 (4H, 2O)
ParenthesesGrouping used in formulas to indicate multiple atoms within a polyatomic ion or a complex structure.Al₂(SO₄)₃ (Aluminum Sulfate)Aluminum (Al), Sulfur (S), Oxygen (O)17 (2Al, 3S, 12O)
Polyatomic IonA group of atoms covalently bonded together that act as a single charged entity.NH₄⁺ (Ammonium)Nitrogen (N), Hydrogen (H)5 (1N, 4H)

Examples of Counting Atoms in a Compound

Chemical FormulaElements PresentTotal Atoms
H₂O (Water)H, O3 (2H, 1O)
CO₂ (Carbon Dioxide)C, O3 (1C, 2O)
CH₄ (Methane)C, H5 (1C, 4H)
NaCl (Salt)Na, Cl2 (1Na, 1Cl)
H₂SO₄ (Sulfuric Acid)H, S, O7 (2H, 1S, 4O)
C₆H₁₂O₆ (Glucose)C, H, O24 (6C, 12H, 6O)

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