He kupu whānui mō ngā rōpū matū ka hangaia ki ētahi pūmotu e rua, nui ake rānei, e hono tahi ana. Kāore e taea te wehewehe ngā pūmotu o tētahi pūhui mā te tukanga ōkiko (pērā i te tātari). Mā te tauhohe matū kē e wehewehe ai. He rerekē ngā āhuatanga ōkiko me ngā āhuatanga matū o tētahi pūhui i ō ngā pūmotu i hangaia ai taua pūhui. Ka pūmau tonu te ōwehenga o ngā pūmotu o tētahi pūhui. Hei tauira, e rua ngā ngota hauwai (H) ka hono atu ki te ngota hāora (O) kotahi, ka hua ko te rāpoi ngota wai (H2O). He pūhui te nuinga o ngā momo matū o ia rā.
A general term for groups of substances composed of two or more elements bonded together. The elements of a compound cannot be separated by a physical process such as filtration, but only through a chemical reaction. The physical and chemical properties of a compound are different from its constituent elements. The ratio of the constituent elements of a compound are fixed, for example, two hydrogen atoms bond to a single oxygen atom to form a molecule of water (H2O). Most everyday substances are compounds.