How many neutrons are in calcium?

1 Answer
May 24, 2017

Answer:

#"Usually 20 neutrons............"#

Explanation:

Why #"usually.........?"#

Every calcium nucleus contains 20 positively charged, nucular particles, #"20 protons"#. This is what defines the nuclide as a calcium nucleus, i.e. #Z=20#. However, the nucleus can contain varying numbers of neutrons. Most calcium nuclei (approx. 97%) contain #20# neutrons.........to give the #""^40Ca# isotope. There are much smaller percentages of the #""^42Ca# and the #""^44Ca# isotopes. The weighted average of all the isotopic masses gives the atomic mass reported on the Periodic Table, i.e. #40.1*g*mol^-1#. Clear?