Matter is all around us, so it's a good idea to know what it is, and why it matters. Learn about matter, its categories, and its subcategories with this interactive lesson.

Wikipedia provides the definition of the term, "Atomic number," a term used in chemistry and physics to represent the number of protons in the nucleus of an atom.

Study chemical bonding in chemistry including atoms, valence electrons, ionic and covalent bonding, and how molecules are formed on this site!

This lesson will define an isotope and demonstrate how to determine the average atomic mass of an element. It is 2 of 9 in the series titled "Isotopes."

This lesson will define an isotope and demonstrate how to determine the average atomic mass of an element. It is 8 of 9 in the series titled "Isotopes."

This lesson will define an isotope and demonstrate how to determine the average atomic mass of an element. It is 4 of 9 in the series titled "Isotopes."

Learn about naming chemical compounds in chemistry including conventions, the order of the elements, metals, non-metals, acids, and examples on naming on this site.

Get some information about some famous chemists who made impacts on their fields! These scientists helped to develop the laws of chemistry and discovered many of the elements.

This lesson will introduce isotopes, and explain how they differ from other elements. It will also show that some isotopes are unstable and emit particles and/or radiation. It is 7 of 9 in the series titled "Isotopes."

This lesson will introduce isotopes, and explain how they differ from other elements. It will also show that some isotopes are unstable and emit particles and/or radiation. It is 5 of 9 in the series titled "Isotopes."

Kids learn about separating mixtures in chemistry including separation processes such as filtration, distillation, and the centrifuge.

Kids learn about organic chemistry including the importance of carbon, organic molecules, compounds, hydrocarbons, synthesis, and functional groups.

Study the science of isotopes in chemistry including naming isotopes, hydrogen, examples, fun facts, unstable, and stable on this site.

A site discussing chemical reactions in chemistry including reaction rate, types of reactions, reagents, reactants, catalysts, and inhibitors.

Explore all about chemical mixtures on this site including solutions, alloys, suspensions, colloids, dissolving, examples, and facts.

When two or more atoms combine they give rise to a molecule. A molecule can be made up of many atoms of the same element. There are 112 elements known to man, so can you imagine the different permutations and combinations of molecules...

Created to teach students of the 21st century, SOPHIA is bringing matter straight to your fingertips. Become the commander of your own learning experiences as you take part in this interactive tutorial. [1:02]

The atoms around you have existed for billions of years- and most originated in the flaming, gaseous core of a star. Dennis Wildfogel tells the captivating tale of these atoms' long journeys from the Big Bang to the molecules they form...

This lesson focuses on the periodic table and the configurations. In the modern periodic table, elements are in order of atomic number in periods and groups. Electronic configurations model how electrons are arranged in atoms. A link to...

Find out the basic characteristics and main properties of all matter.

[Free Registration/Login Required] Explore the composition of air and learn about the different atoms and molecules that we breathe every day.

Activity 1 in this module: What is the effect of changing the composition of an atom? Since all atoms contain protons, neutrons, and electrons, what makes one element different from another is examined.

[Free Registration/Login may be required to access all resource tools.] Discusses elements, atoms, compounds, molecules, and crystals. Looks at mixture and different types of them.

Through this reading, students will learn that a substance's properties arise from its molecular structure, not from how it's made (i.e., synthesized by people or found in nature). There is no fundamental difference between natural and...