WJEC Chemistry for AS: Student Bk

Unit 1 Content 57 The periodic table 57 Electronic structures 57 Electron transfer in oxidation/reduction Trends in ionisation energy, etc. 58 Chemistry of Group 1 and Group 2 elements and compounds 59 Chemistry of Group 7, the halogens 59 Use of halogens in water treatment 60 Practical work – quantitative and qualitative analysis The periodic table is an essential tool in dealing with the vast number of chemical elements and compounds that exist enabling us to see trends and make predictions. In this topic we see how the table is set up and operates and study the important chemistry of the s-block Group 1 and 2 elements and compounds and the halogens in Group 7. 1.6 The periodic table You should be able to demonstrate and apply knowledge and understanding of: ▪ The arrangement of elements in the table in terms of the electronic structures in the s, p and d blocks. ▪ Oxidation and reduction in terms of electron transfer. ▪ The trends in ionisation energy, electronegativity and physical properties across periods and down groups. ▪ The common reactions of the s-block elements with water, acids and oxygen and their flame colours. ▪ The common reactions of Group 2 ions with hydroxide, carbonate and sulfate ions and the thermal stability and solubility trends of the common salts. ▪ The reaction of the halogens with metals and the trend in their volatility. ▪ Their relative oxidising power and understand the redox displacement reactions. ▪ The reaction of halide ions with Ag + followed by dilute ammonia. ▪ The use of chlorine and fluoride ions in water sterilisation. ▪ How to perform simple gravimetric analysis and salt formation and crystallisation. ▪ How to identify unknown solutions by logic and qualitative analysis. 56