Molecular Weight Calculator

How to Calculate Molecular Weight

The molecular weight (or molar mass) of a compound is the mass of one molecule of that substance, expressed in atomic mass units (u) or grams per mole (g/mol). To find it, you simply sum the atomic weights of all the atoms in the chemical formula.

Step-by-Step Guide:

1. Identify the Elements: Break down the chemical formula into individual element symbols (e.g., H₂O becomes H and O).
2. Count the Atoms: Note the subscript number after each symbol. If there is no number, it implies 1 atom. For example, H₂ means 2 Hydrogen atoms.
3. Find Atomic Weights: Use the periodic table above to find the standard atomic weight for each element.
4. Multiply and Sum: Multiply the atomic weight of each element by the number of its atoms in the molecule, then add all the results together.

Common Chemical Compounds Reference

Below is a reference table for the molecular weight of common substances used in chemistry, biology, and industry.

Understanding the Periodic Table

The periodic table organizes all known chemical elements by increasing atomic number and recurring chemical properties. Understanding the color coding in our interactive tool can help predict element reactivity:

• Alkali Metals (Red): Highly reactive metals, soft, and often stored in oil to prevent reaction with air or water.
• Alkaline Earth Metals (Orange): Shiny and silvery-white, somewhat reactive at standard conditions.
• Transition Metals (Yellow): Good conductors of heat and electricity; often used in construction and technology.
• Noble Gases (Purple): Colorless, odorless gases with very low chemical reactivity.