Explore covalent bonding through animated dot-and-cross shell diagrams in the style of GCSE textbooks and exam papers. Select atoms or choose familiar molecules, then watch electrons form shared pairs. Investigate single, double and triple bonds, identify lone pairs, check completed outer shells and connect diagrams with molecular and displayed formulae. Additional sections explain the electrostatic attraction holding bonded atoms together and link the structures of molecular substances, diamond, graphite, graphene, silicon dioxide, fullerenes and polymers to their properties. Built-in diagram questions provide immediate feedback. Suitable for GCSE teacher demonstrations, guided exploration and independent revision. simopsis