The ionic model

Learning objectives

Explain the formation of cations and anions by the loss or gain of electrons, and predict the charge of a common ion from the position of the element in the periodic table

Describe an ionic bond as the electrostatic attraction between oppositely charged ions in a three-dimensional lattice, and deduce the formula of an ionic compound including those containing polyatomic ions such as nitrate, sulfate, carbonate, hydroxide and ammonium

Name ionic compounds from their formulas and write formulas from their names, using Roman numerals where an element has more than one common oxidation state

Explain the high melting and boiling points, brittleness, electrical conductivity when molten or in solution but not when solid, and solubility in polar solvents of ionic compounds in terms of the lattice

Predict and explain the relative melting points of ionic compounds from the charges and radii of the ions

Deduce the ionic or covalent character of a binary compound from the difference in electronegativity between the two elements, recognising that the change is gradual rather than sharp