How to set Non Bonding Electron Pairs

Go with the mouse cursor over the red point where you want to set electron pairs.

The electron pairs are set with the keys of the numeral keyboard:

8/2 up/down - 4/6 left/right

7,9,1,3 sets the electron pairs in an angle of 45°.

By repeated pressing the keys of the numeral keyboard you may display the electrons as dots or remove the pairs completely. When you want to do so, the mouse pointer has to be placed over the red point.