This image shows the tricky topic structure for atomic structure theory. The first orange rectangle identifies the stumbling block ‘atomic structure theory’. This box is connected, by a black line, to four green stumbling blocks labelled ‘understanding space in atomic model’, ‘understanding energy levels’, ‘understand charges’ and ‘visualize atom and subatomic particles’. The first stumbling block ‘understanding space in atomic model’ is linked by a green line to one problem example box labelled ‘problem seeing atoms have different sizes and mass’. The second stumbling block ‘understanding energy levels’ is linked to two problem example boxes labelled ‘can’t see trends and differences in groups in periodic table’ and ‘inability to predict reactant and products’. The third stumbling block, ‘understand charges’ is linked to two problem examples labelled ‘recognizing charges of protons, neutrons and electrons’ and ‘confusion about repulsion and attraction’. The fourth stumbling block ‘visualize atom and subatomic particles’ is linked to four problem examples ‘difficulty with terminology of subatomic model’, ‘confusion about repulsion and attraction’, ‘problem seeing atoms have different sizes and mass’ and recognizing charges of protons, neutrons and electrons.