CK-12 Foundation
Ck 12: Isotopes and Atomic Mass
[Free Registration/Login may be required to access all resource tools.] In the following online tutorial students will be asked to define atomic number, mass number and understand how isotopes differ from one another. They will be able...
Chem Tutor
Chem Tutor: Atomic Structure: Atomic Weights and Atomic Numbers
This lesson explains many basic concepts of atomic structure. It starts with atomic mass and number and then works up to more sophisticated information on electron configuration and how each element fits into the Periodic Table.
OpenStax
Open Stax: Elements and Atoms, the Building Blocks of Matter
This site provides an overview of elements and atoms, the building blocks of matter.
Science Struck
Science Struck: List of Radioactive Elements
Learn about radioactivity, the different types of radioactive decay, isotopes, and half-life of a radioactive element. Includes a long chart listing radioactive elements, atomic number and mass number, decay type, and length of half-life.
Texas Education Agency
Texas Gateway: Ap Physics I: Appendices: Atomic Masses
This is a chart of the elements including the atomic mass, atomic number, symbol, half-life, and more.
Wikimedia
Wikipedia: Atomic Number
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.
CK-12 Foundation
Ck 12: Physical Science: Atomic Number
[Free Registration/Login may be required to access all resource tools.] Definitions of atomic number and mass number.
Environmental Chemistry
Environmental chemistry.com: Anatomy of an Atom
Explains the basics of atomic structure, from simple definitions to information about quantum theory. Accurate and helpful basics whether or not you need the more advanced information.
CK-12 Foundation
Ck 12: Physical Science: Atomic Number
[Free Registration/Login may be required to access all resource tools.] Definitions of atomic number and mass number.
Science Struck
Science Struck: How to Find Protons, Neutrons and Electrons
Brief explanations of how to determine how many protons, neutrons, and electrons are in an element.
Encyclopedia of Earth
Encyclopedia of Earth: Elements
Engaging and very informative article that explains what elements are, some of their history, how they are represented, the categories of elements, the periodic table, and how they are structured and classified.
Science Struck
Science Struck: Periodic Table With Atomic Mass
Explains how Dmitri Mendeleev created the periodic table of elements, how it was organized, the changes made by Henry Moseley in 1931, some characteristics of element groups, and what the atomic mass, number, and abbreviation each...
California State University
California State University: Proton, Electron, Neutron
An interesting and useful tool to practice recognition/calculation of atomic number, mass, and number of neutrons, electrons, etc. Can be used with all elements.
Mocomi & Anibrain Digital Technologies
Mocomi: Structure of an Atom
An atom is made of three parts - protons, neutrons, and electrons. Here you can explore these different parts.