# Question f0510

Dec 10, 2016

Here's how you can do that.

#### Explanation:

All you really need to know in order to find the number of electrons in your ion is the atomic number of the element, which gives you the number of protons present in the nucleus, and it net charge.

More specifically, the relationship between the number of protons present in the nucleus, the number of electrons that surround the nucleus, and the net charge of the ion is given by

$\textcolor{red}{\underline{\textcolor{b l a c k}{\text{no. of protons " - " no. of electrons" = " net charge}}}}$

In your case, the atomic number is equal to $12$, so you know that

$\text{no. of protons} = 12$

The net charge is equal to $2 +$, which means that you have

$\text{12 protons" - color(purple)(?)color(white)(.)"electrons} = + 2$

Rearrange to solve for the number of electrons

color(darkgreen)(ul(color(black)(color(purple)(?) = "12 protons" - 2 = "10 e"^(-))))#

Keep in mind that the mass number gives you the number of protons and neutrons present in the nucleus.

$\textcolor{red}{\underline{\textcolor{b l a c k}{\text{mass number" = "no. of protons " + " no. of neutrons}}}}$

In this case, you have

$26 = \text{12 protons" + "14 neutrons}$

Therefore, you can say that your ion has

$\left\{\begin{matrix}\text{12 protons" \\ "14 neutrons" \\ "10 electrons" \\ "a 2"+ " charge}\end{matrix}\right.$