IB›IB Chemistry SL›Mind mapsS2.1 The ionic modelIB Chemistry SL: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsForming ionsMetals lose electrons: cationsNon-metals gain electrons: anionsAim for noble-gas configurationMg loses 2 → MgX2+\ce{Mg^2+}MgX2+N gains 3 → NX3−\ce{N^3-}NX3−Ionic bondElectrostatic attraction between opposite ionsForms a 3D lattice, not moleculesEach NaX+\ce{Na+}NaX+ has six ClX−\ce{Cl-}ClX− neighboursStronger with higher charge, smaller radiusFormulasBalance positive and negative chargesMgX2+\ce{Mg^2+}MgX2+ and NX3−\ce{N^3-}NX3− give MgX3NX2\ce{Mg3N2}MgX3NX2Binary names end in -ide-ate ions contain oxygenBrackets for repeated ions: CaX3(POX4)X2\ce{Ca3(PO4)2}CaX3(POX4)X2Ionic modelions and latticesNa⁺Cl⁻Mg²⁺O²⁻Polyatomic ionsAmmonium NHX4X+\ce{NH4+}NHX4X+Nitrate NOX3X−\ce{NO3-}NOX3X−, hydroxide OHX−\ce{OH-}OHX−Carbonate COX3X2−\ce{CO3^2-}COX3X2−, sulfate SOX4X2−\ce{SO4^2-}SOX4X2−Phosphate POX4X3−\ce{PO4^3-}POX4X3−PropertiesHigh melting point, low volatilitySolid does not conduct: ions fixedMolten or aqueous conducts: ions moveSoluble in polar solvents like waterInsoluble in non-polar solventsExam tipsIonic bonding is not sharing electronsIons carry charge, not electronsMgO melts higher than NaCl: charge