# Question #0bebd

May 1, 2016

$\text{Cu}$, ${\text{Zn}}^{+}$, ${\text{Ga}}^{2 +}$

#### Explanation:

As you know, the ratio of protons to electrons will determine if an atom is neutral or if it carries an overall net charge.

More specifically, you have three possible scenarios to consider

• if you have equal numbers of protons and of electrons $\to$ the atom will be neutral
• if you have more protons than electrons $\to$ the atom will have an overall positive charge
• if you have more electrons than protons $\to$ the atom will have an overall negative charge

So, you know that you have $29$ electrons to work with here. The only way to get a neutral atom that has $29$ electrons surrounding its nucleus is if you give it $29$ protons inside its nucleus.

A quick look in the periodic table will show that the element that has an atomic number equal to $29$, i.e. $29$ protons located inside its nucleus, is copper, $\text{Cu}$.

A neutral copper atom will thus have $29$ protons located inside its nucleus and $29$ electrons surrounding its nucleus.

To form a positively charged ion, or cation, you can keep the number of electrons constant and add one or more protons to the nucleus.

If you add one proton, you'll end up with $30$ protons inside the nucleus. The element that has an atomic number equal to $30$ is zinc, $\text{Zn}$.

Since you now have an extra proton compared to the number of electrons, you'll end up with a $1 +$ charge on the atom $\to {\text{Zn}}^{+}$.

Adding two protons will get you to gallium, $\text{Ga}$, the element that has $31$ protons inside the nucleus.

This time, you have two extra protons compared with the number of electrons, so the overall charge will be $2 +$. The cation will thus be ${\text{Ga}}^{2 +}$.