ACSI 2022 HL Chemical Bonding and Structure Core (Teacher) (1)

IBDP Chemistry HL/Chemical Bonding and Structure Page 1   Anglo − Chinese School (Independent) Year 5 (2022) IBDP Chemistry HL (IBDP syllabus Topic 4) 4.1 Ionic bonding and structure - Essential Idea: ionic compounds consist of ions held together in lattice structures by ionic bonds. 4.2 Covalent bonding - Essential Idea: covalent compounds form by the sharing of electrons. 4.3 Covalent structures - Essential Idea: Lewis (electron dot) structures show the electron domains in the valence shell and are used to predict molecular shape. 4.4 Intermolecular forces - Essential Idea: the physica l properties of molecular substances result from different types of forces between their molecules. 4.5 Metallic bonding - Essential Idea: metallic bonds involve a lattice of cations with delocalised electrons     TOPIC 4 CHEMICAL BONDING AND STRUCTURE TEACHER COPY – WITH SUGGESTED SOLUTIONS

IBDP Chemistry HL/Chemical Bonding and Structure Page 3   Introduction  A chemical bond is a force which holds two or more atoms or ions together.  All chemical reacti ons involve bond breaking followed by bond making. o The breaking of bonds requires (absorbs) energy – endothermic process. o The formation of bonds releases e nergy – exothermic process. The feasibility of a reaction depends on the energy transfers a ssociated with the breaking and making of bonds. Hence, by forming bonds with each other, atoms become part of a more stable system.  All types of bonding involve interactions between opposite cha rges and they are electrostatic in nature. o Ionic bond – attraction between some positively charged particles (cations) and negatively charged particles (anions) o Covalent bond – attraction between nuclei and shared electrons o Metallic bond – attraction between metal ions and delocalised electrons  The electrons involved in the chemical bond formation usually come from the outermost shells of the atom s. These electrons are called valence electrons. The nuclei of the atoms are unaffect ed. The valence electrons rearr ange to attain a state of minimum energy.  Usually, atoms achieve stabili ty by acquiring the nearest nobl e gas electronic configuration. This means possessing a completely filled valenc e shell with 8 outermost shell electrons. This is known as octet configuration . Helium is an exception because it has only two electrons.  Bonding affects the chemical and physical properties of compounds.

IBDP Chemistry HL/Chemical Bonding and Structure Page 4   HF, NH3, H2O, CH3COOH, CH3CH2OH, CH3CONH2 3 types CHEMICAL BONDING IONIC BONDING COVALENT BONDING (incl Coordinate Covalent Bonds) METALLIC BONDING Giant Ionic Structure Simple Molecular Structure Giant Covalent Structure (Macromolecular Structure) Giant Metallic Structure Hydrogen Bon