Andaikan anda menggosok sekeping besi dengan kertas pasir. Tiba-tiba angin bertiup ke arah anda dan sedikit serbuk besi masuk ke dalam mata anda. Anda berjumpa doktor dengan segera. Ramalkan kaedah pengasingan yang digunakan oleh doktor untuk mengeluarkan serbuk besi daripada mata anda.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.