the Physics Education Technology Project
This simulation promotes understanding of isotopes by providing a simple way to model isotopes of the first 10 elements in the Periodic Table. In the most basic model, users click on an atomic symbol. The simulation displays a stable isotope for that atom. (For example, choose Helium and view a nucleus with two protons and two neutrons.) Now, drag neutrons into the nucleus and watch to see if atom becomes unstable. Students may be surprised to see that Beryllium and Flourine, for example, are unstable with equal numbers of protons and neutrons in the nucleus. Click on "Abundance in Nature" to see how common or rare a particular isotope is in nature. Mass number and Atomic Mass (amu) are displayed in real time.
See Related Materials for a lesson plan developed specifically for use with the "Isotopes and Atomic Mass" simulation.
This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET).
Please note that this resource requires
Java Applet Plug-in.
6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
6-8: 4D/M1b. The atoms of any element are like other atoms of the same element, but are different from the atoms of other elements.
9-12: 4D/H1. Atoms are made of a positively charged nucleus surrounded by negatively charged electrons. The nucleus is a tiny fraction of the volume of an atom but makes up almost all of its mass. The nucleus is composed of protons and neutrons which have roughly the same mass but differ in that protons are positively charged while neutrons have no electric charge.
9-12: 4D/H2. The number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons.
9-12: 4D/H3. Although neutrons have little effect on how an atom interacts with other atoms, the number of neutrons does affect the mass and stability of the nucleus. Isotopes of the same element have the same number of protons (and therefore of electrons) but differ in the number of neutrons.
9-12: 4D/H4. The nucleus of radioactive isotopes is unstable and spontaneously decays, emitting particles and/or wavelike radiation. It cannot be predicted exactly when, if ever, an unstable nucleus will decay, but a large group of identical nuclei decay at a predictable rate. This predictability of decay rate allows radioactivity to be used for estimating the age of materials that contain radioactive substances.
9-12: 4D/H5. Scientists continue to investigate atoms and have discovered even smaller constituents of which neutrons and protons are made.
11. Common Themes
6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.
6-8: 11B/M4. Simulations are often useful in modeling events and processes.
6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.
%0 Electronic Source %D July 8, 2011 %T PhET Simulation: Isotopes and Atomic Mass %I Physics Education Technology Project %V 2017 %N 29 March 2017 %8 July 8, 2011 %9 application/java %U https://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass
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This is a lesson plan appropriate for Grades 7-10, created specifically to accompany the "Isotopes and Atomic Mass" simulation. It is very effective at guiding beginning students through an exploration of the atomic nucleus and factors that affect the stability of an atom.