Ionic Compounds Flashcards

All 6 cards in this deck

What type of structure does an ionic compound have?

A giant structure (lattice) of ions.

What holds an ionic compound together, and in which directions do these forces act?

Strong electrostatic forces of attraction between oppositely charged ions, acting in all directions in the lattice.

What are the steps to work out the empirical formula of an ionic compound from a model of its lattice?

e.g. a model showing 4 $\mathrm{Mg^{2+}}$ ions and 4 $\mathrm{O^{2-}}$ ions

1. Count the ions of each type: 4 and 4.
2. Write the simplest whole number ratio: $1:1$.
3. Write the formula with the positive ion first: $\mathrm{MgO}$.

Give one limitation of using a dot and cross diagram to represent a giant ionic structure.

It shows electron transfer but not the giant three-dimensional arrangement, sizes or spacing of the ions.

Give one limitation of using a ball and stick model to represent a giant ionic structure.

It shows gaps (sticks) between ions that are not really there, and only a small part of the lattice, not to scale.

True or false? Sodium chloride is made up of separate NaCl molecules.

False. Sodium chloride is a giant ionic lattice of $\mathrm{Na^+}$ and $\mathrm{Cl^-}$ ions; NaCl is its empirical formula.