The mass number of common krypton is 84, and its atomic number is 36. krypton-84 has how many neutrons within each isotope?

1 Answer
Jun 23, 2016

Answer:

#"48 neutrons"#

Explanation:

The mass number, #A#, of a given isotope tells you the number of protons, #Z#, which is given by the atomic number, and neutrons it has in its nucleus.

#color(blue)(|bar(ul(color(white)(a/a)A = Z + "no. of neutrons"color(white)(a/a)|)))#

In your case, krypton-84 is said to have a mass number equal to

#A = 84#

This means that the nucleus of a krypton-84 isotope contains a total of #84# protons and neutrons.

Since the element has an atomic number equal to #36#, it follows that it will contain #36# protons in its nucleus. Therefore, the number of neutrons present in the nucleus of a krypton-84 isotope will be

#"no. of neutrons" = A - Z#

#"no. of neutrons" = 84 - 36 = color(green)(|bar(ul(color(white)(a/a)color(black)(48)color(white)(a/a)|)))#

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