Magnesium oxide is made up of ${\mathrm{Mg}}^{2+}$ ions and ${\mathrm{O}}^{2–}$ ions. How does the amount of charge present on the ions in an ionic compound affect the melting and boiling points? Explain your reasoning.

The strength of an ionic bond is also dependent on the distance between the two ionic centres. How are the melting and boiling points are affected by the ionic radius of the interacting ions? Sodium chloride has a melting point of $801 °\mathrm{C}$ and a boiling point of $1,413°\mathrm{C}$. Caesium has a larger ionic radius than sodium, and iodine has a larger ionic radius than chlorine. How do the melting and boiling points of sodium chloride and caesium iodide compare? Explain your reasoning.

Do you expect magnesium oxide, $\mathrm{MgO}$, to be more soluble or less soluble than sodium chloride? Explain your reasoning.

Scientists use three-dimensional visualisations or models to enable a clear understanding of the concept being examined. How do other professions use modelling or simulations to convey meaning?

What did you observe when you placed the seed crystal into the saturated solution (while investigating a supersaturated solution)?

Draw conclusions on what is happening to the solubility of the salt as the temperature of the solution decreases. Support your discussion with scientific reasoning.

What does the position of an element in the periodic table tells us whether it is classified as a metal or a non-metal?

What does the position of an element in the periodic table tells us about what group it belongs to and from this guess some of the properties common to this group?

What does the position of an element in the periodic table tells us about the number of valence electrons it has?