The chart is about atomic structure: at the top, the left box is "nucleus" and the right is "electron cloud".
On the left, under nucleus, the two boxes are: "protons" on the right and "neutrons" on the left. Under proton is elements which is given and under neutrons, it is "isotopes".
On the right, under electron cloud, the next box is "electrons" and then the lower box is "ions".