What you’ll learn3 learning objectivesChoose one objective for a focused lesson, or study the complete topic.3.4.1Covalent bonding examples• Define covalent bonding as attraction between two nuclei and a shared electron pair.- Describe covalent bonding in H2, O2, N2, Cl2, HCl, CO2, NH3, CH4, C2H6 and C2H4- Period 3 expanded octets: SO2, PCl5 and SF6- Coordinate bonding: NH3 + HCl -> NH4+ and Al2Cl6Syllabus objective3.4.2Sigma and pi bonds• Describe covalent bonds by orbital overlap.- Sigma bonds: direct overlap between bonding atoms- Pi bonds: sideways overlap of adjacent p orbitals above and below the sigma bond- Apply to H2, C2H6, C2H4, HCN and N2; use sp, sp2 and sp3 hybridisationSyllabus objective3.4.3Terms• Gaseous state- (a) define the terms:- bond energy as the energy required to break one mole of a particular covalent bond in the- bond length as the internuclear distance of two covalently bonded atoms- (b) use bond energy values and the concept of bond length to compare the reactivity of covalent moleculesSyllabus objective