A zinc atom has 30 electrons around its nucleus. There are 2 in the K shell, 8 in the L shell, 18 in the M shell and 2 in the N shell.
Zinc loses the two electrons in its outer N shell to become a doubly charged positive ion, \mathrm{Zn}^{2+}. Because the M shell is full with 18 electrons, \mathrm{Zn}^{2+} is the only ion zinc forms, and its solutions are colourless.
Zinc is an amphoteric metal: it reacts both with acids, such as hydrochloric acid, and with strong bases, such as sodium hydroxide solution, giving off hydrogen.
\mathrm{Zn} + 2\mathrm{HCl} \longrightarrow \mathrm{ZnCl_2} + \mathrm{H_2}
\mathrm{Zn} + 2\mathrm{NaOH} + 2\mathrm{H_2O} \longrightarrow \mathrm{Na_2[Zn(OH)_4]} + \mathrm{H_2}
To make hydrogen in the laboratory, dilute sulfuric acid is added to zinc.
When a little sodium hydroxide solution is added to a solution containing \mathrm{Zn}^{2+}, white zinc hydroxide, \mathrm{Zn(OH)_2}, is precipitated. When more is added, the precipitate dissolves and the solution becomes colourless again.
With ammonia solution, too, a white precipitate forms first and then dissolves when more is added.
The precipitate of aluminium hydroxide does not dissolve when ammonia solution is added, so this difference can be used to tell zinc and aluminium apart.
Iron sheet coated with zinc is called galvanized iron, and it has long been used for roofs and buckets.
Even if galvanized iron is scratched and the iron is exposed, the zinc, which forms ions more readily than iron, dissolves first, so the iron is still protected from rust. Protecting a metal in this way, by letting a metal that forms ions more readily dissolve first, is called sacrificial protection.
In zinc-carbon dry cells and alkaline dry cells, zinc is used as the negative electrode. The zinc loses electrons to become \mathrm{Zn}^{2+}, and the electrons flow through the wire to the positive electrode.
Zinc mixed with copper makes the alloy brass, which is used for Japan's 5-yen coin and for brass instruments. Zinc oxide, \mathrm{ZnO}, is a white powder used in paints, sunscreens and ointments.
Zinc is also needed by the body, and a lack of it can make it harder to taste things.