Shared pairs and full shells
Shared pairs and full shells
Atoms bond using their outer-shell electrons, and for the non-metals here the group number tells you how many outer electrons they have. Hydrogen aims for 2 electrons in its outer shell, while carbon, nitrogen, oxygen and the halogens usually become stable with 8.
Step-by-step lessons on Edexcel IGCSE Chemistry Covalent bonding. Each one builds up to exam-style questions. Build a solid grasp of atomic structure, bonding and the mole concept early, since these underpin almost every other topic, then move on to the more calculation-heavy quantitative and organic chemistry content.