Difference Between a Coefficient and a Subscript

Difference Between a Coefficient and a Subscript
••• apichon_tee/iStock/GettyImages

Coefficients and subscripts are essential components when writing longhand chemical formula compounds or equations. A coefficient, reflecting the number of molecules in a given substance, is a number placed in front of a given molecule’s abbreviation. A subscript, however, reflecting each element’s atomic contribution to a given molecule, appears following or between elemental abbreviations and is typically smaller in size and set below the type line.

Coefficient Example

The chemical equation for creation of water molecules, or H2O, is one that uses coefficients. In this equation, two molecules of hydrogen, or 2H2, bond with two molecules of oxygen, or 2O2, to yield two molecules of water, or 2 H2O. As this example illustrates, the use of coefficients allows for an accounting of the number of each molecule included in a chemical reaction as well as a means of balancing chemical equations and determining the limiting reagents in a given equation. For example, this reaction, written completely as 2H2 + 2O2 = 2H2O, shows that hydrogen and oxygen must be present in equal proportions to maximize the amount of water molecules produced.

Subscript Example

The formula for baking soda, or NaHCO3, gives an example of a subscript. As this formula reflects, there is one atom each of the elements of sodium, or Na, hydrogen, or H, and carbon, or C. The subscript of 3 following the symbol for oxygen, or O, reveals that three atoms of oxygen are needed for every Na, H and C atom to make a complete molecule of baking soda.

Related Articles

How to Find the Number of Moles Needed to React
How to Write a Chemical Compound Formula
What Is the Number Written to the Left of the Chemical...
How to Calculate a Fraction Covalent
How to Calculate the Stoichiometric Ratio
How to Determine Moles in Chemistry
Understanding Chemical Formulas
What Conversion Factor is Present in Almost All Stoichiometry...
How to Balance Chemistry Equations
How to Calculate the Moles of a Compound
How to Tell if a Molecule Is Bent
How to Determine How Many Hybrid Orbitals
How to Calculate Factorials
How to Determine Delta H
What Are Representative Particles of Elements?
What Are Subscripts in a Chemical Formula Used to...
How to Count Particles in Chemical Formulas
How to Factor Trinomials on a TI-84
How to Calculate a Milliequivalent
What Are True Statements About a Compound?