Names & Formulae of Ionic Compounds Flashcards

All 6 cards in this deck

What does the ending –ate tell you about a compound?

It contains a compound ion that includes oxygen.

e.g. copper sulfate contains $\mathrm{SO_4^{2-}}$.

Give the formulae of the hydroxide, nitrate, carbonate and sulfate ions.

$\mathrm{OH^-}$, $\mathrm{NO_3^-}$, $\mathrm{CO_3^{2-}}$, $\mathrm{SO_4^{2-}}$.

What are the steps to deduce the formula of an ionic compound from its ions?

e.g. $\mathrm{Mg^{2+}}$ and $\mathrm{Cl^-}$

1. Write the two ions with their charges: $\mathrm{Mg^{2+}}$, $\mathrm{Cl^-}$
2. Choose numbers of each ion so the charges cancel to zero: one $\mathrm{Mg^{2+}}$ to two $\mathrm{Cl^-}$
3. Write the formula without charges: $\mathrm{MgCl_2}$

When do you need brackets in the formula of an ionic compound?

e.g. $\mathrm{Ca^{2+}}$ with $\mathrm{NO_3^-}$

When more than one compound ion is needed, so the number applies to the whole ion.

e.g. $\mathrm{Ca(NO_3)_2}$.

True or false? The formula of calcium carbonate is $\mathrm{Ca(CO_3)_2}$.

False. It is $\mathrm{CaCO_3}$, because $\mathrm{Ca^{2+}}$ and $\mathrm{CO_3^{2-}}$ balance one to one.

True or false? The formula of an ionic compound has no overall charge, because the total positive charge of the cations equals the total negative charge of the anions.

True. The ions combine in the ratio that makes the compound electrically neutral, e.g. $\mathrm{Mg^{2+}}$ and $\mathrm{Cl^-}$ give $\mathrm{MgCl_2}$.