What makes isotopes alike

However, isotopes are not always available in sufficient quantities or at reasonable prices. The program produces and distributes radioactive and stable isotopes that are in short supply, including byproducts, surplus materials, and related isotope services. The program also maintains the infrastructure required to produce and supply priority isotope products and related services. Finally, it conducts research and development on new and improved isotope production and processing techniques.

Scientific terms can be confusing. DOE Explains offers straightforward explanations of key words and concepts in fundamental science. Hydrogen and its two naturally occurring isotopes, deuterium and tritium. Isotope Facts All elements have isotopes. These two ways include writing a nuclear symbol or by giving the name of the element with the mass number written.

To write a nuclear symbol , the mass number is placed at the upper left superscript of the chemical symbol and the atomic number is placed at the lower left subscript of the symbol.

The complete nuclear symbol for helium-4 is drawn below:. The following nuclear symbols are for a nickel nucleus with 31 neutrons and a uranium nucleus with neutrons.

In the nickel nucleus represented above, the atomic number 28 indicates that the nucleus contains 28 protons, and therefore, it must contain 31 neutrons in order to have a mass number of The uranium nucleus has 92 protons, as all uranium nuclei do; and this particular uranium nucleus has neutrons. Another way of representing isotopes is by adding a hyphen and the mass number to the chemical name or symbol.

Thus the two nuclei would be Nickel or Ni and Uranium or U, where 59 and are the mass numbers of the two atoms, respectively. Note that the mass numbers not the number of neutrons are given to the side of the name. This page was constructed from content via the following contributor s and edited topically or extensively by the LibreTexts development team to meet platform style, presentation, and quality:.

Learning Objectives Explain what isotopes are and how an isotope affects an element's atomic mass. Determine the number of protons, electrons, and neutrons of an element with a given mass number. An Example: Hydrogen Isotopes Hydrogen is an example of an element that has isotopes. What is the atomic number and the mass number of an isotope of lithium containing 4 neutrons? Solution A lithium atom contains 3 protons in its nucleus irrespective of the number of neutrons or electrons.

Stability of Isotopes Atoms need a certain ratio of neutrons to protons to have a stable nucleus. The complete nuclear symbol for helium-4 is drawn below: The following nuclear symbols are for a nickel nucleus with 31 neutrons and a uranium nucleus with neutrons. To find the number of neutrons, subtract the number of protons from the mass number. Summary The number of protons is always the same in atoms of the same element. The number of neutrons can be different, even in atoms of the same element.

Atoms of the same element that contain the same number of protons, but different numbers of neutrons, are known as isotopes. Isotopes of any given element all contain the same number of protons, so they have the same atomic number for example, the atomic number of helium is always 2. This is referred to as its half-life, or the time it takes for half of the original concentration of an isotope to decay back to its more stable form.

Because the half-life of 14 C is long, it is used to date formerly-living objects such as old bones or wood. Comparing the ratio of the 14 C concentration found in an object to the amount of 14 C in the atmosphere, the amount of the isotope that has not yet decayed can be determined. On the basis of this amount, the age of the material can be accurately calculated, as long as the material is believed to be less than 50, years old.

This technique is called radiocarbon dating, or carbon dating for short. Other elements have isotopes with different half lives.

For example, 40 K potassium has a half-life of 1. Scientists often use these other radioactive elements to date objects that are older than 50, years the limit of carbon dating. Through the use of radiometric dating, scientists can study the age of fossils or other remains of extinct organisms. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Atoms, Molecules, and Ions.

Search for:.