# Question #a9f0d

Nov 2, 2017

$\text{_19^41"K}$

#### Explanation:

As you know, when a radioactive nuclide undergoes electron capture, an electron located in one of the inner shells is absorbed by the nucleus. In the process, a proton is converted to a neutron and an electron neutrino, ${\nu}_{\text{e}}$, is emitted.

So right from the start, the fact that a proton is being converted to a neutron tells you to things

In your case, calcium, $\text{Ca}$, has an atomic number equal to $20$, which means that the resulting nuclide will have

$Z = 20 - 1 = 19$

The element that has an atomic number equal to $19$ is potassium, $\text{K}$. Since the mass number remains unchanged, you can say that the resulting isotope will be potassium-41.

So you can say that the nuclear equation that describes the electron capture of calcium-41 looks like this

$\text{_ 20^41"Ca" + ""_ (-1)^(color(white)(-)0)"e" -> ""_ 19^41"K" + nu_ "e}$

Notice that you have

• $41 + 0 = 41 \text{ "" } \to$ conservation of mass
• $20 + \left(- 1\right) = 19 \to$ conservation of charge