Write the lewis structure for mgi2. draw the lewis dot structure for mgi2. include all lone pairs of electrons.

Lewis Structure is drawn in following steps,

1) Calculate Number of Valence Electrons:
    
# of Valence electrons in Mg  =  2
# of Valence electrons in I      =  7
# of Valence electrons in I      =  7
                                               ---------
Total Valence electrons          =  16

2) Draw Mg as a central atom surround it by two atoms of Iodine.

3) Connect each Iodine atom to Mg, and subtract two electrons per bond. In this case we will subtract 4 electrons from total valence electrons. i.e.

Total Valence electrons           16
- Four electrons                    -   4
                                              ----------
                                                  12

4) Now start adding the remaining 12 electrons on more electronegative atoms i.e. Iodine.

The final lewis structure formed is as follow, 

The disturbance is only parallel to the motion of the wave.