Ions become from atoms.
When the atom loses or gains some electrons, it becomes an ion.
If it loses electrons, we have a cation, which is a positive ion. Otherwise, if it gains, we have a negative ion or anion.
a) Chlorine: Cl (nonmetal), tends to gain electrons.
Cl ion: Cl-1
b) Cesium: Cs (metal), tends to lose electrons.
Cs ion: Cs+1
c) Nitrogen: N(nonmetal), tends to gain electrons