Answer:

1. oppositely charged ions.

• An ionic bond is the force of attraction that holds together oppositely charged ions. It forms when atoms of a metal transfer electrons to atoms of a nonmetal. When this happens, the atoms become oppositely charged ions. As a result, ionic compounds are brittle solids with high melting and boiling points.

2. Lonization energy is the energy required to remove electrons from gaseous atoms or ions.

• When forming an ionic bond, one atom must form a cation by losing one or more electrons. Ionization energy decreases down a group in the periodic table due to the fact that the outermost electrons are further away from the nucleus.