IGCSE›Edexcel IGCSE Chemistry›Mind maps2.2 Group 7 (Halogens)Edexcel IGCSE Chemistry: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsAppearanceChlorine: pale green gasBromine: red-brown liquidIodine: grey-black solid, purple vapourDarker colour down the groupPhysical trendMelting and boiling points increaseBigger molecules, stronger intermolecular forcesFluorine: pale yellow gasAstatine: predicted dark solidDisplacementMore reactive halogen displaces less reactive halideClX2+2 KI→2 KCl+IX2\ce{Cl2 + 2KI -> 2KCl + I2}ClX2+2KI2KCl+IX2Colourless KBr turns orange with chlorineBromine cannot displace chlorineGroup 7the halogensFClBrIAtReactivity trendReactivity decreases down the groupHalogens gain one electron → 1− ionBigger atoms, more shieldingHarder to gain an electronVersus Group 1Group 7: harder to gain down the groupGroup 1: easier to lose down the groupOpposite reactivity trendsExam tipsGive colour and state togetherHalogens never lose electrons to reactUse the trend to predict F and At