‹ All simulationsChemistry · AS Level 9701 · 3 Chemical bondingEight simulations covering Topic 3: shapes of molecules, dot-and-cross diagrams, ionic and metallic bonding, electronegativity and polarity, sigma and pi bonds, intermolecular forces, and how structure decides properties. Rotate the 3D scenes with drag, zoom with the wheel or pinch.
Electron pairs around the central atom repel and move as far apart as possible. Lone pairs repel more than bonding pairs, so they squeeze the bond angles. Pick a molecule and rotate it; lone pairs are drawn as translucent lobes.
Outer-shell electrons only. Dots belong to one atom, crosses to the other, and a shared pair sits in the overlap. In a dative (coordinate) bond both electrons come from the same atom, so the overlap holds two of the same symbol. Step through the diagram or show it all at once.
Sodium gives one electron to chlorine. The ions then pack into a giant lattice where every Na⁺ touches six Cl⁻ and every Cl⁻ touches six Na⁺. The bonding is the electrostatic attraction between oppositely charged ions in every direction, not a bond between one pair.
A lattice of positive ions in a sea of delocalised electrons. The attraction between the ions and the electron sea holds the metal together. Apply a potential difference and the electrons drift, so the metal conducts. Push the layers and they slide without breaking the bonding, so the metal is malleable.
Electronegativity is the power of an atom to attract the bonding electrons. A big difference makes a polar bond with δ+ and δ− ends. Whether the whole molecule is polar depends on the shape: symmetrical molecules cancel their bond dipoles.
A sigma bond is end-on overlap along the line between the nuclei. A pi bond is sideways overlap of p orbitals above and below that line. Build ethene step by step: hybridise, form the sigma framework, then add the pi bond.
Forces between molecules are much weaker than covalent bonds, but they decide melting and boiling points. Watch the three kinds in action, then read the hydride boiling points: the group 14 hydrides rise smoothly with size, while NH₃, H₂O and HF sit far above the trend because of hydrogen bonding.
Five structures, five very different materials. Compare a giant ionic lattice, two giant covalent structures, a simple molecular solid and a metal. The melting point tells you what has to be broken; the conductivity tells you whether anything charged can move.