What happens to electrons when an ionic bond forms?
Electrons are given to other atoms/received from other atoms
Ionic bonding is simply the electrostatic forces of attraction between ions, and ions have charge, because they have more electrons/less electrons than they do protons.
Therefore ionic bonding is the bonding between metals and non-metals. Each atom strives to achieve a full outer shell of electrons. Metals have an excess and non-metals have a dearth of electrons, so electrons from the metal are transferred to the non-metal, giving the metal a positive charge, and the non-metal a negative charge, thus they attract each other.