# What is the net charge of an ion that has 8 protons, 9 neutrons, and 10 electrons?

Jan 17, 2016

$2 -$

#### Explanation:

For a given atom, net charge can be determined by looking at how many protons the atom has in its nucleus and how many electrons it has surrounding its nucleus.

More specifically, the atom will have

• a positive net charge if it has more protons in its nucleus than electrons surrounding its nucleus

• a negative net charge if it has more electrons surrounding its nucleus than protons in its nucleus

• no net charge if it has equal numbers of protons and electrons

When an atom carries a positive net charge, it forms a cation, or positively charged ion. Likewise, when an atom carries a negative net charge, it forms an anion, or negatively charged ion.

In your case, the atom is said to contain

• eight protons
• nine neutrons $\to$ they do not influence the net charge of the atom
• ten electrons

Now, electrons and protons carry opposite charges. A proton is said to carry a $1 +$ charge, while an electron is said to carry a $1 -$.

In your case, you have $8$ protons and $10$ electrons. This means that the atom will carry a total

$2 \times \left(1 -\right) = 2 -$

net charge.

Therefore, you are dealing with an anion that carries a $2 -$ net charge, i.e. it has two more electrons than it does protons.