Chemical Bonding and Structure structured questions · SEC G3 Pure Chemistry

Learning objectives

• describe the formation of ions by electron loss/gain and that these ions usually have the electronic configuration of a noble gas
• describe, including the use of ‘dot-and-cross’ diagrams, the formation of ionic bonds between metals and non-metals, e.g. NaCl; MgCl2
• state that ionic materials contain a giant lattice in which the ions are held by electrostatic attraction, e.g. NaCl (candidates will not be required to draw diagrams of ionic lattices)
• relate the physical properties (including electrical property) of ionic compounds to their lattice structure (see also 3.4(g)).
• describe the formation of a covalent bond by the sharing of a pair of electrons and that the atoms in the molecules usually have the electronic configuration of a noble gas
• describe, using ‘dot-and-cross’ diagrams, the formation of covalent bonds between non-metallic elements, e.g. H2; O2; H2O; CH4; CO2
• deduce the arrangement of electrons in other covalent molecules
• relate the physical properties (including electrical property) of covalent substances to their structure and bonding (see also 3.4(g)).
• describe metals as a lattice of positive ions in a ‘sea of electrons’
• describe the general physical properties of metals as solids having high melting and boiling points, malleable, good conductors of heat and electricity in terms of their structure (see also 3.4(g)).
• describe the differences between elements, compounds and mixtures
• describe an alloy as a mixture of a metal with another element, e.g. brass; stainless steel
• identify representations of metals and alloys from diagrams of structures
• explain why alloys have different physical properties to their constituent elements
• compare the structures of the following substances in order to deduce their properties: — simple molecular substances, e.g. methane, iodine
• compare the structures of the following substances in order to deduce their properties: — macromolecules, e.g. poly(ethene)
• compare the structures of the following substances in order to deduce their properties: — giant covalent substances, e.g. sand (silicon dioxide), diamond, graphite (see also 3.4(g))
• compare the bonding and structures of diamond and graphite in order to deduce their properties such as electrical conductivity, lubricating or cutting action (candidates will not be required to draw the structures)
• deduce the physical and chemical properties of substances from their structures and bonding and vice versa (see also 3.1(d), 3.2(d), 3.3(b) and 3.4(e)).