# How many neutrons does calcium have?

Nov 26, 2015

In calcium-40, there are 20 neutrons.

#### Explanation:

The number of neutrons can be found with the formula:

Number of neutrons = mass number - atomic number

Calcium:
mass number = $40.08 \Rightarrow 40$
atomic number = $20$

Number of neutrons = relative atomic mass - atomic number
Number of neutrons = $40 - 20$
Number of neutrons = $20$

Nov 26, 2015

It depends on the isotope.

#### Explanation:

Calcium's atomic number is 20, which means all calcium atoms have 20 protons in their nuclei. However, the number of neutrons in the nuclei of the calcium atoms can vary. Atoms of the same element with different numbers of neutrons are isotopes.

There are many isotopes of calcium, ranging from calcium-40 with 20 neutrons, to calcium-48 with 28 neutrons.

For more on the isotopes of calcium, refer to the following website. https://en.m.wikipedia.org/wiki/Calcium