Adrian Dingle, Educator and Chemistry Author with 25 years teaching experience
- A chemical change involves the formation of a brand new substance.
Chemical changes are described by chemical equations where bonds are broken and made in order to form entirely new substances. At the AP level, we characterize the bonds that are being broken/made in chemical changes (reactions) as intra bonds (ionic and covalent).
Chemical changes often come with some observable change such as; production of a gas, a color change, production of a solid (a precipitate) or some kind of energy change (temperature goes up or down)
- A physical change involves no new substances being formed, but rather the same substances being present but in a different form. The most common physical change would be a change of state from, for example, solid to liquid etc.
Physical changes can also be described by chemical equations, BUT here only the state symbols would change (there are no new substances formed). Here, only intermolecular forces are broken and made. At the AP level, we characterize the forces that are being broken/made in physical changes as intermolecular forces (H-bonds, London dispersion forces, dipole-dipole).