Isotopes
Two forms of an element with the same atomic number but different mass number. The presence of isotopes can be understood by looking over the structure of atoms.
All atoms contain three kinds of basic particles 1. protons 2.neutrons 3.electrons. The protons and neutrons in an atom are found in the atomic nucleus while the electrons are found in the space around the nucleus.
The number of protons in a nucleus defines an atom. Hydrogen atoms all contain one proton in their nucleus. Helium atoms contain two protons in their nucleus. Lithium atoms contain three protons in their nucleus and on and on and on. The amount of protons in an atom's nucleus is its atomic number. Hydrogen has an atomic number of 1. Helium an atomic number of 2. Lithium has an atomic number of 3. Another way of defining isotopes is that they are different forms of an atom with the same number of protons but different numbers of neutrons.
Most elements have at least two stable isotopes. The use of stable here means not radioactive. Twenty elements, including fluorine, sodium, aluminum, phosphorus, and gold, have only one stable isotope.
All atoms contain three kinds of basic particles 1. protons 2.neutrons 3.electrons. The protons and neutrons in an atom are found in the atomic nucleus while the electrons are found in the space around the nucleus.
The number of protons in a nucleus defines an atom. Hydrogen atoms all contain one proton in their nucleus. Helium atoms contain two protons in their nucleus. Lithium atoms contain three protons in their nucleus and on and on and on. The amount of protons in an atom's nucleus is its atomic number. Hydrogen has an atomic number of 1. Helium an atomic number of 2. Lithium has an atomic number of 3. Another way of defining isotopes is that they are different forms of an atom with the same number of protons but different numbers of neutrons.
Most elements have at least two stable isotopes. The use of stable here means not radioactive. Twenty elements, including fluorine, sodium, aluminum, phosphorus, and gold, have only one stable isotope.
Representing Isotopes
There are two ways isotopes are represented. One, they may be directed by putting down the name of the element followed by the mass number of the isotope. The two forms of helium are called helium-4 and helium-3. Two, isotopes may be directed by the chemical symbol of the element with a superscript that shows their mass number. The designations for the two isotopes of helium are 4He and 3He.
(2009,Science clairified)
