When a divalent ion of these elements forms a tetrahedral complex, it obeys the octet rule.

This virtual cathode then attracts the ions formed inside the thruster closer to the anode.

The positive ion from a base and the negative ion from an acid form a salt together.

So why would such ions form in the first place?

Scattered ions form shadow cones (see above) behind each atom, which prevents any backscattering at low incidence angles.

These ions form soluble salt compounds which dry on the surface; these salts are washed away during the next wet season.

It is believed that ions, such as those of iron, form a Wigner crystal in the interiors of white dwarf stars.

The ions thus formed can be separated by m/z with mass spectrometry.

Fixed and mobile ions form a double layer.

The attracted ions thus form a layer balancing the electrode's charge.