An isotope is an atom that contains a different number of neutrons than its base chemical element. Each element is defined by its respective number of protons. The atomic number of an element refers to its proton count a... More »

The isotopes of an element differ from each other in their mass numbers and the number of neutrons they contain. All of the isotopes of an element, however, contain the same number of protons, which is equal to that elem... More »

All isotopes of the same element share a common number of protons and electrons, though they vary in their relative numbers of neutrons. All isotopes of a given element are chemically identical, and they form bonds with ... More »

To find the mass number of an element or isotope, add the neutrons and protons in one atom. Hydrogen is just one element with multiple isotopes occurring naturally, appearing in atomic form with just one proton (mass num... More »

There are 13 neutrons in an atom of the isotope magnesium-25. The number of the isotope refers to the number of nuclear particles in general; subtracting 13 neutrons means that there are 12 protons at the nucleus. More »

Atomic mass is a measure of the mass of a single atom of a single isotope of an element when it is at rest, while atomic weight is a somewhat more complicated measurement that takes into account the relative abundance of... More »

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The number of neutrons in barium depends on what isotope of barium it is. The most common types of barium are barium-138 and barium-137, which have 82 and 81 neutrons respectively. Barium also has 56 protons and 56 elect... More »