The elements of group 1 makes ionic bond with the elements of group 7 due to high difference of electronegativity values.
The elements of first group lose its one outermost electrons while on the other hand, the elements of seven group needs one electron so they gain that one electron so they make an ionic bond with each other.
So we can conclude that the elements of group 1 makes ionic bond with the elements of group 7 because of the high difference of electronegativity values.
Learn more about electronegativity here: https://brainly.com/question/2415812