Explain the difference between a positive ion and a negative ion.

1)An element forms a positive ion when it loses an electron called Cation, whereas it forms a negative ion when it gains an electron called Anion.
2) Cations have smaller atomic radii than that of an Anions.
3) Metals have the tendency to form Cations by losing an electron, while non metals have tendency to form Anions by gaining an electron.
4) etc

Variables,control,conclusion and finally scientific theory