Chemistry - Molecules and their Composition - Online course| Alison

Chemistry - Molecules and their Composition - Revised

Learn more about molecular formulas, empirical formulas, and Avogadro's number with this free chemistry course.

Free Course
In this free online chemistry course, you will learn about molecules and how they are composed of various elements in mass, atoms, and ratios. A molecule is a group of two or more atoms that bind together using chemical bonds. They may be from one or multiple elements and it is the ratio, or mass composition, of each molecule that gives the molecular compound its chemical characteristics. Take this course to learn more about molecules today!
  • Duration

    1.5-3 Hours
  • Certification

  • Mobile Friendly

  • Publisher

    Khan Academy
  • Accreditation






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Molecules are made up of atoms and are the smallest particle in a chemical element or compound. This course will introduce you to the fundamentals of molecules and their composition. You will study molecular formulas, which are essentially the actual number of atoms in a molecule, and empirical formulas which tell you what people have observed. You will also study the mole and Avogadro's number which is equal to 6.023 × 10 to the power of 23.

You will then study molecular formulas and empirical formulas from the mass composition and learn how to balance chemical equations. This course will also discuss stoichiometry which is the study or the calculation of the relationships between the different molecules in a reaction. You will also learn about the limiting reagent which is basically the reactant that produces the least amount of product. You will also study how to solve mass composition problems.

Learning how to convert between atomic mass and grams using Avogadro’s number or the Mole is one of the important topics you will study in this course. Once you have mastered this, you will be able to easily work out ratios and weights of molecules. You will also learn how to balance chemical equations, and get viable chemical reactions by balancing the reactants within equations. So, check out this course and learn more about stoichiometry today!

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Learning Outcomes

Having completed this course you will be able to:

  • Outline the empirical, molecular and structural formulas
  • Use the Periodic Table and the 'amu' to work out weights and ratios
  • Convert between Avogadro's number (moles) and grams
  • Derive the empirical structure from the mass composition
  • Demonstrate how to balance a chemical equation


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